PREFACE 

In the year nineteen hundred and six in the audacity of youth I ventured to apply a comprehensive title to what was in reality a comparatively small selection from the contents of Leonardo da Vinci's Notebooks} I have now attempted to redeem the promise of my title in some degree of completeness. More than half a century ago, when the work of transcription of the Leonardo manuscripts was first commenced, a controversy arose among scholars as to whether the best method of publication was by individual manuscripts or collectively with some attempt at classification. Time has a way of proving most controversies vain, and in this instance it has shown the essential Tightness of the position of both disputants. The publication of the transcripts of the original manuscripts, with facsimiles, has served as the foundation of all subsequent study. Some classification of the material, however, has been found to be necessary on account of the extraordinary diversity of the subjects treated of in the same manuscript, in the majority of cases. Leonardo himself admitted as much in a prefatory note to the manuscript now in the British Museum (Arundel 263), and the action of Pompeo Leoni in compiling the Codice Atlantico out of other manuscripts by the use of scissors and paste has only made confusion worse confounded. I have therefore arranged the subject-matter under various main headings, but beyond this I have made no change of order, the passages in each section appearing in the same sequence as in the manuscripts, those of Milan coming first followed by those in Paris, London and Windsor. In the few cases, however, in which the whole or substantially the whole of a manuscript falls within the same section I have given it priority, e.g. in Anatomy', 'Flight', Tainting', and 'Optics'. About a dozen pictures are all that can be  attributed to Leonardo with any degree of certitude or even of probability, and the witness of contemporary record, however credulously interpreted, does not do more than double or treble the number. How he disposed of his time would be an enigma but for the existence of the vast collection of drawings, and particularly of the notebooks. These number upwards of five thousand pages, the contents of which I have attempted to classify under some fifty headings. The classification is, as I know, rough and imperfect, this the wellnigh infinite variety of the contents having rendered almost inevitable. For, of this man who did a few works of art most divinely well, it may be said that he took all knowledge as his province, and that in his individual achievement he symbolizes the diversity of an epoch as fully as can be said of any man at any period in the world's history. To one who has studied them intermittently for more than a quarter of a century these manuscripts  the product of how many thousand hours of intellectual activity! are the records of the working of the mightiest machine perhaps that has ever been a human brain: fragments of a larger purpose, charted, defined, explored, but never fulfilled, of which the treatises containing the sum of his researches in anatomy, physiology and geology form component parts, fragments of a vast encyclopedia of human knowledge. 

What thinker has ever possessed the cosmic vision so insistently? 

He sought to establish the essential unity of structure of all living things, the earth an organism with veins and arteries, the body of a man a type of that of the world. The perceptions of his brain are hardly if at all fettered by bondage of time and place. At rare times, however, the personal note supervenes and moods of exultation or depression flash out their meaning in a phrase. The mood of the seer finds expression in fable or allegory, or in the series of 'the Prophecies', revealing the depth of his mordant humour and his power of analysis of the motives which guide human conduct, or in speculation as to results that would follow possible extension of man's power — in which time has confirmed his prescience and his foreboding. 

The manuscripts are a wellnigh inexhaustible quarry in which the student of every phase of Leonardo's mental activity will find material. 
They are of peculiar value for the biographer, both in their revelation of personality and in the manner in which they react on contemporary record. Thus they tend to confirm Vasari in his more picturesque statements. He has told how Leonardo when he passed the places where birds were sold would often take them from their cages, pay the price demanded, and restore their liberty by letting them fly into 
the air. 'The goldfinch', wrote Leonardo, 'will carry spurge to its little ones imprisoned in a cage — death rather than loss of liberty.' The purport of the note becomes clear from the fact that certain varieties of the spurge form a violent poison. His account of how Leonardo 
collected lizards, hedgehogs, newts, serpents and all sorts of strange creatures, and from these constructed the head of a hideous monster, 
when in his youth he received a commission to paint something on a shield which should cause terror to the beholder, is directly confirmed 
by the painter's own precept, 'how to make an imaginary animal appear real'; the method being that each part should have a basis of reality, 
thus the body of a serpent, head of a mastiff or setter, eyes of cat, ears of porcupine, nose of greyhound, eyebrows of lion, temples of an old 
cock and neck of turtle. So also with reference to Leonardo's activities as master of pageant at the Court of Milan, the automatic lion which 
according to Vasari formed part of the pageant on the occasion of the entry of the French King, that advanced a few steps and opened its breast to show it filled with lilies, is drawn in different positions on a page of the Anatomy MSS. at Windsor. 

The letters and fragments of letters are also of primary importance for the biographer. They sound the whole gamut of sensations from the proud confidence of the first letter to Ludovic and that to the Commissioners of the Cathedral of Piacenza, through the terse appeals of the later days in Milan when 'the horse' was ready for the casting and foreign subsidies had exhausted the Treasury, to those written in the depression of the Roman period, when his hopes of employment had been frustrated and he had been denounced to the Pope for his practice of anatomy, while his nerves were reacting helplessly to the misbehaviour of an apprentice. 

Of the real ultimate value of the results of Leonardo's various scientific researches and investigations I have no title to attempt to speak. They can be judged only by specialists, and when a section is thus passed under review the result from the time of Dr. William Hunter onwards has been to confirm the impression of their great worth, esestablishing him as a thinker of very exact powers of analysis as well as a fertile investigator whose work shows a firm grasp of the principles of experimental science. For example, among the anatomical investigations which find record in the Windsor Manuscripts is that of the spinal cord and intestines of the frog. 'The frog', he says, 'retains life for some hours when the head, the heart, and all the intestines have been taken away. And if you prick the said cord it instantly twitches and dies' (Quaderni V 21 r.). On the reverse of the same sheet is written: 'the frog instantly dies when the spinal cord is pierced; and previous to this it lived without head, without heart, or any bowels or intestines or skin; and here therefore it would seem lies the foundation of movement and life.' 

The originality of his methods of anatomical investigation is illustrated by the details he gives of the making of wax casts in order to 
discover the true form of the ventricles of the brain: 

'Make two air holes in the horns of the great ventricles and insert melted wax by means of a syringe, making a hole in the ventricle of the memoria, and through this hole fill the three ventricles of the brain; and afterwards when the wax has set take away the brain and you will see the shape of the three ventricles exactly. But first insert thin tubes in the air holes in order that the air which is in these ventricles may escape and so make room for the wax which enters into the ventricles' (Quaderni V 7 r.). Leonardo, as the learned editors of the Quaderni d'Anatomia inform 
us, was the first to make casts of the cerebral ventricles, and several hundred years elapsed before the idea occurred to any other anatomist. 
It is on the fringe of this uncharted knowledge that the gift of expression often haunts and tantalizes by its beauty. 

'Every weight tends to fall towards the centre by the shortest way' (C 28 v.) is the kernel of Newton's law of gravitation. 'The earth is 
moved from its position by the weight of a tiny bird resting upon it. The surface of the sphere of the water is moved by a tiny drop of water 
falling upon it' (B.M. 19 r.). Is this also the language of mechanics? In the section of his treatise on 'Painting', in which he institutes 
comparison between painting and the other arts, he has no divided allegiance; but, in 'the Prophecies', he has expressed his sense of the 
potentialities of literature, although somewhat enigmatically: 'Feathers shall raise men even as they do birds, towards heaven; that is by letters 
written with their quills.' 

Although disclaiming for himself all title to the rank of literary artist he displays a remarkable power of lucid expression, so that his language seems exactly to mirror his thought and his phrases arrest by their simplicity. This literary quality pervades his humour, which is on 
occasion terse and trenchant, e.g. 'that venerable snail the sun'; 'Man has great power of speech but the greater part thereof is empty and 
deceitful. The animals have little but that little is useful and true; and better is a small and certain thing than a great falsehood'. The latter 
sentence might fitly serve as proem to the 'A Bestiary' in Manuscript H, where it is stated of the great elephant that he has by nature qualities which rarely occur among men, namely probity, prudence, and the sense of justice and of religious observance. There is perhaps something of the same mood to be discerned in the instruction that the leather bags, intended to prevent an aviator from doing himself any harm if he chance to fall a height of six braccia on water or on land, should be tied after the fashion of the beads of a rosary; or when after referring to the damage caused to great things by the firing of a cannon he speaks of the spiders' webs being all destroyed. So also where under the rubric 'Of local movement of flexible dry things' he discusses the movement of dust when a table is struck — of the dust which is separated into various hillocks descending from the hypotenuse of these hillocks, entering beneath their base and raising itself round the axis of the point of the hillock, and so moving as to seem a right-angled triangle. One finds one's self wondering when if ever the table was dusted, and reflecting as to how much his powers of observation would have been cramped by matrimony. I have not considered it necessary to transcribe the numerous pages 
of Latin declensions and conjugations or the various portions of a Latin-Italian glossary which are to be found in Manuscript H of the 'Institut'. It has been suggested that they were compiled for the instruction of Maximilian and Francesco Sforza, who were born in January 1493 and February 1495, and whose features are familiar as they kneel in chubby complacency in the Zenale altar-piece in the Brera ; and the elder of whom is the boy seen sitting reading Cicero in the fascinating fresco by a Milanese painter now in the Wallace Collection. It is some what difficult to fit Leonardo into the part of a private tutor to the Sforza princes although he performed various functions at the court, but it is quite possible that these lists, although as usual they are in 'left-handed writing', were compiled for the purpose of imparting information. The fact that the allegories about animals, which are for the most part a compilation from Pliny and medieval bestiaries, are also found in Manuscript H suggests the possibility that if the Latin grammar and glossary were written for the instruction of the Sforza princes, Leonardo's book of beasts may have been put together for their edification as a sort of antidote, so that the acerbities of the Latin conjugations might be varied by such rare and refreshing fruit as the story of the amphisbaena — a four-footed beast that resembled the Push mipullyou of Hugh Lofting's Dolittle books in having a head at each end, both of which, however, discharged poison, unlike those of the modern story. Leonardo's imagination is seen perhaps in completest 
freedom in the fragment of a fantastic tale in the form of letters, in the Codice Atlantico. The giant of such stature that when he shook his head he dislodged showers of men who were clinging to the hairs, is a fantasy curiously suggestive of the actions of Gulliver in Lilliput. 

The problem of the interpretation of the letters purporting to be written from Armenia has been a vexed question ever since Dr. Jean Paul Richter made their existence known. The evidence, I think, tends to confirm the view that they are a record of fact and that Leonardo was for a time in the East, nor as it seems to me is this interpretation rendered untenable as Dr. Verga would seem to suggest, by the circumstance of Leonardo having used the classical nomenclature of Ptolemy in these letters. The references to books which occur in Leonardo's manuscripts show that he was in the habit of studying all classical and medieval authorities obtainable on the subjects in which he was interested. Ptolemy was one of the chief sources from which he gratified his curiosity as to the distant and dimly recorded places and peoples of the earth. Pliny, Strabo, and even Sir John Mandeville also figure in the category. The system of nomenclature of Ptolemy supplied the forms he must inevitably have used in expressing his first conceptions of distant places. The same consideration must certainly have operated in the minds of many contemporary travelers. Geography was one of the sciences in which the knowledge of classical literature may be said to have lain like a dead hand. Leonardo's debt to Ptolemy was great. In a passage in his treatise on anatomy in which he described how his system of dissection of the various parts of man is to be so co-ordinated that the result may reveal the structure or mechanism of the whole body, he pays a tribute to Ptolemy as a master of synthetic arrangement whom he is proud to follow: 'therefore there shall be revealed to you here in fifteen entire figures the cosmography of the "minor mondo" [the Microcosmos or 'lesser world'] in the same order as was used by Ptolemy before me in his cosmography'. May not his debt to tolemy have been much the same in the one case as in the other — in the one the arrangement, in the other the nomenclature, and perhaps the first interest in places ? 

The manuscripts are the repository of much practical wisdom designed to sweeten the intercourse of life and revealing itself in divers unexpected ways. A social reformer might profitably stand upon the precept : 'Let the street be as wide as the universal height of the houses'. The evils of absentee landlordism and those resulting from the amassing of huge estates — 'field laid unto field, that they may be placed alone in the midst of the earth' — are alike exorcized in the sentence, 'Happy is that estate which is seen by the eye of its lord'. Riches had lost some of their chief lures for the man who could write thus : 'Small rooms or dwellings set the mind in the right path, large ones cause it to go 
astray'; and, 'Wine is good but water is preferable at table'. 

The golden mean in all things — failing this, renunciation. 'Entbehren sollst du, sollst entbehren.' 'Neither promise yourself things nor do things', he wrote, 'if you see that when deprived of them they will cause you material suffering'. The sentence serves to recall a remark once uttered by Dr. Jowett on the subject of smoking: 'Do not set up for yourself any new necessities'. 

This practical sense is always perceptible when he is discussing the subject of art. In his 'Botany for Painters' he pauses in the act of defining the laws of branch structure to address the painter who, as he recognizes, is bound to be unacquainted with these laws, and to assure him that he may escape the censure of those who have studied them if he is zealous to represent everything according to Nature. So also in discussing the flight of birds (C.A. 214 r. a) he turns for parallel to the movement of the fish's tail; and this, he says, may be proved with a pair of oars. And in stating the variation in a bird's weight as it spreads itself out or draws itself together (E 43 v.) he adds, 'and the butterflies make experiments of this in their descents'. At times, however, the operation of this practical sense is obscured by the insistence upon primary laws: e.g. 'In order to give the exact science of the movement of the birds in the air it is necessary first to give the science of the winds, and this we shall prove by means of the movements of the water. This science is in itself capable of being received by the senses: it will serve as a ladder to arrive at the knowledge of flying things in the air and the wind' (E 54 r.). 

Of the closeness and exactness of his power of observation certain of the anatomical drawings afford example, equally with the studies for pictures. The lines seem to have the spontaneity and inevitability of life itself. The same power translated is visible in his descriptions of Nature in her changeful moods. These have something of the effect of studies taken with a camera at close range. As when for example he speaks of the waves made by the wind in May running over the cornfields without the ears of corn changing their place; of reeds scarcely visible in the light but standing out well between the light and the shade (L 87 r.) ; of waves which intersect after the manner of the scales of a fir cone, reflecting the image of the sun with the greatest splendour because the radiance of so many reflections is blended together (B.M. 25 r.) ; of water in impact with a larger fall turning like the wheel of a mill (F 81 r.). A statement in the Leicester Manuscript (13 r.) as to the surface of tiny shadowed waves shaping itself in lines that meet in an angle, as though formed by the sand, this being proof of its shallowness, might serve as an exact description of the treatment of waves in Botticelli's 'Birth of Venus', as also in certain of his illustrations to Dante. Botticelli, who frequented Verrocchio's studio when Leonardo was there as a pupil, is the only one of his Florentine contemporaries whose practice was cited by him in his writings on art. While thus on the one hand his teaching might serve to interpret the practice of Botticelli, it bridges the wellnigh bottomless gulf in which the votaries of classicism forgather, and anticipates the freedom of composition and subtilty of atmospheric effects of the period of naturalism. His precept that the mind should seek stimulation to various inventions from the spectacle of the blend of different stains on a wall, postulates utmost liberty in arrangement. The most delicate evanescent effects of Anton Mauve, or of Courbet at the time when he painted his 'Duck Shooter', are brought before us by such a sentence as the following:

'No opaque body is without shadow or light except where there is a mist lying over the ground when it is covered with snow, or it will be the same when it snows in the country' (Quaderni II 6 r.).

 Similarly the spirit of Whistler's creations is evoked in the directions under the rubric, 'How to represent white figures' (MS. 2038 Bib. Nat. 20 r.) ; and Turner's most characteristic effects are recalled by the ethereal simplicity and directness of Leonardo's description of the phenomena of sunrise : 

'At the first hour of the day the atmosphere in the south near to the horizon has a dim haze of rose-flushed clouds; towards the west it grows darker, and towards the east the damp vapour of the horizon shows brighter than the actual horizon itself, and the white of the houses in the east is scarcely to be discerned; while in the south, the farther distant they are, the more they assume a dark rose-flushed hue, and even more so in the west; and with the shadows it is the contrary, for these disappear before the white' (C.A. 176 r. b). 

Who having witnessed the sequence of the effects of sunrise from the angle of observation afforded by a hilltop, can doubt Leonardo's description to be a record of what he had actually seen? 'Pre-imagining — the imagining of things that are to be. Post- imagining — the imagining of things that are past.' So in a passage in the Windsor Manuscripts Leonardo defines with singular felicity two fields of thought over which his spirit ranged with a freedom only limited by the necessity of interpreting natural phenomena. The Leicester Manuscript contains the sum of his researches in the natural history of the earth; in the records that time has written in the rocks and the high deposits of the mountain ranges, of the period when as he says 'above the plains of Italy where now birds fly in flocks fishes were wont to wander in large shoals'. 'Sufficient for us', he states, 'is the testimony of things produced in the salt waters and now found again in the high mountains far from the seas.' Elsewhere in the same manuscript he refers to the discovery of a prehistoric ship found during the digging of a well on the country estate of one of Ludovic Sforza's retinue, and the decision taken to change the position of the well in order to leave it intact. In a passage in the Arundel Manuscript he apostrophizes as a once-living instrument of constructive nature the form of a great fish whose bones despoiled and bare, as it lies in a hollow winding recess of the hills of Lombardy, are become as an armour and support to the mountain that lies above it. The lines seem charged with just such sensations as must have animated that first scientist in the Dordogne whom a fortunate chance led to enter the caves of Les Eyzies. But it is in the realm of pre-imagining, 'the imagining of things that are to be', that the manuscripts constitute the most impressive revelation of his creative thought. That a single mind could conceive and anticipate the growth of knowledge at such divers points as the circulation of the blood, the heliocentric theory, the law of inertia, the camera obscura, is only to be believed because the evidence for it exists. 

In the fragment of a torn letter written apparently to Ludovic Sforza during the embarrassed later years of his rule in Milan, Leonardo reveals how disastrous from the standpoint of the artist were the exigencies of the time. The same may also be said with regard to the conditions which prevailed over Europe during a considerable period of the Great War : the arts put to silence and altar-piece and fresco hidden away in bomb-proof shelters or protected with sand-bags. To the completeness of this silence, however, as affecting the great names in art, that of Leonardo formed a unique exception. In war as in peace the course of events demonstrated that as Siren has said, 'no one can be indifferent to Leonardo'. All the most characteristic developments of the Great War, those which distinguish it from all in the long roll of its predecessors — the use of the bombing aeroplane, the use of poison gas, the tank and the submarine — all afford examples of his prescience. He foretold the construction of each, not with the enigmatic utterance of the seer, but with such precision of scientific and mechanical detail as would be natural in one who held, as did Leonardo, the office of military engineer in the Romagna under Caesar Borgia during the brief tenure of his power, and had offered his services in a similar capacity to Ludovic Sforza. It may seem something of an enigma that such activities should have emanated from the brain of one who has stigmatized warfare as 'bestialissima pazzia' (most bestial madness). The clue to its solution is to be found, however, in a passage in one of the Leonardo Manuscripts in the Bibliotheque Nationale (MS. 2037, 10 r.) in which he refers to the difference between offensive and defensive warfare, and emphasizes the necessity of preparation for the one as a safeguard of all that life holds most dear: 'When besieged by ambitious tyrants I find a means of offence and defense in order to preserve the chief gift of Nature, which is liberty', and so he goes on to speak first of the position of the walls, and then of how people may maintain their good and just lords. 

He envisaged the scientific possibilities of the use of poison gas in naval warfare, gave a formula for its composition and described how a mask might be made to act as a preventive. It is impossible lightly to assume that Leonardo, who has written: 'It is an infinitely atrocious thing to take away the life of a man', would have regarded the use of poison gas against the civil population as permissible under any circumstances. 

The prototype of the tank or armoured car appears in one of Leonardo's drawings in the British Museum. He has thus foreshadowed its use in breaking the line: 'these take the place of the elephants. One may tilt with them. One may hold bellows in them to spread terror among the horses of the enemy, and one may put carabiniers in them to break up every company' (B 83 v.). 

In this as in his attempts to construct a machine for flight, he was hampered by the lack of knowledge of a suitable motive power for propelling such a machine. He studied the laws of flight and the conditions under which it existed in Nature with inexhaustible zeal, and his scientific deductions from these go far to create the type of the modern aeroplane. He thought of flight as man's natural entry into the deferred inheritance of the air, and did not, apparently, foresee that such was man's nature that his wings would inevitably become the wings of war. Had he envisaged the extension of man's power as enabling him to rain death from the skies his attitude might conceivably have been that of the artist in Johnson's Rasselas, of whom it is related that having mastered the art of flying by the invention of wings on the model of those of the bat he refused to divulge his secret. 'If men were all virtuous', he said, 'I should with great alacrity teach them all to fly. But what would be the security of the good, if the bad could at pleasure invade them from the sky ? Against an enemy sailing through the clouds neither walls nor mountains and seas could afford any security. A flight of northern savages might hover in the wind and light at once with irresistible violence upon the capital of a fruitful region that was rolling beneath them. Even this [the Amharic] valley the retreat of princes . . . might be violated.' The conjecture that such would in fact have been Leonardo's attitude is further strengthened by the nature of his remarks, on the subject of the unrestricted use of the submarine. The passage, in the Leicester Manuscript (22 v.), is as follows: 

'How by an appliance many are able to remain for some time under water. How and why I do not describe my method of remaining under water for as long a time as I can remain without food; and this I do not publish or divulge, on account of the evil nature of men, who would practice assassinations at the bottom of the seas by breaking the ships in their lowest parts and sinking them together with the crews who are in 
them.' 

'To preserve the chief gift of Nature which is liberty' — this if not the motive underlying all his study of mechanisms of warfare was undoubtedly a controlling factor; for in the world as he envisaged it there is sovereign liberty for the individual to think and devise. 

As the long labour of preparation of this edition of Leonardo's writings draws to an end, a letter comes to me from the United States telling me of the fact of the Faculty of Princeton University having drawn up a list of ten names of men of all time who have done most to advance human knowledge. The names are: Socrates, Plato, Aristotle, Galileo, Leonardo, Pasteur, Shakespeare, Newton, Darwin and Einstein. No such list is ever likely to win general agreement, for the lack of a common standard of values. It may at any rate be claimed for this one that each name is cut deep in the rock of achievement. In thought of some of the names the strange prescience which has caused Leonardo to be styled 'the forerunner' recurs inevitably to the mind. As, independently of the researches of Galileo, he wrote 'the sun does not move', so he enunciated the root principle of Newton's law of gravitation in the words : 'every weight tends to fall towards the centre by the shortest way'; so also in several passages the nature of which is indicated by such a sentence as the following : 'write of the quality of time as distinct from its mathematical divisions', he would seem to have been pointing along the road which in our own times has been travelled by Einstein. 

Where his energy shows itself most inexhaustible is in the investigation of the working of the elemental forces, as in the sections, 'Movement and Weight' and 'Water'. As water may be seen winding in wonder-working coils through his landscape backgrounds, so with infinite zeal he set himself to study how the elements are situated one within the other, why water moves and why its motion ceases, how it rises in the air through the heat of the sun, and afterwards falls in rain: the artist's love of beauty transforming the scientist's purpose even while he is in the act of wresting from its infinite variety its underlying principles. 

Certain of the results of these investigations formed that volume on 'The Nature of Water' which was one of those seen in the manor house at Cloux near Amboise, where Leonardo passed the last three years of his life, and where in October 15 17 he was visited by a Cardinal of Aragon and his retinue. To the fortunate circumstance of the Cardinal's secretary Antonio de Beads having kept a diary in which he set down particulars of the visit, we owe our knowledge of the fact that the Leonardo manuscripts there formed 'an infinite number of volumes . . . which if they should be published will be profitable and very enjoyable'. 

II 

The early biographers of Leonardo da Vinci cultivated the picturesque with an almost metrical licence. Their narratives, which together constitute what Pater has termed the legend 'e, are as inadequate to reveal his work and personality as the fables of Vulcan's forge and the like are unsatisfying as an origin for Etna's fire. Moreover, in the different aspects which Etna has assumed to the imagination, seeming at first a caprice of the gods and a thing of rhapsody, and subsequently — as the tenor of thought changed — a field for the scientific study of the forces of Nature, there is presented a contrast no less sharply defined, and in its main features somewhat closely corresponding to that presented by the personality of Leonardo as shown in the earliest biographies and in the light of modern research. For the capricious volatile prodigy of youthful genius which the legende has bequeathed, the latter has substituted a figure less romantic, less alluringly inexplicable, but of even more varied and astonishing gifts. His greatness as an artist has suffered no change, but modern research has revealed the ordered continuity of effort which preceded achievement. It has made manifest how he studied the structure of the human frame, of the horse, of rocks and trees, in order the better to paint and make statues, in that his work would then be upon the things he knew, and no sinew or leaf would be conventional, but taken directly from the treasury of Nature; since the artist should be 'the son, not the grandson of Nature'. 

This habit of scientific investigation in inception subsidiary to the practice of his art, so grew to dominate it as to alienate him gradually from its practice to the study of its laws, and then of those which govern all created Nature. The fruits of these studies lay hidden in manuscripts of which the contents have only become fully known within the last half century. So by a curious appositeness he is associated in each age with the predominant current of its activity. His versatility in the arts caused him to seem an embodiment of the spirit of the Renaissance. Alike as painter, sculptor, architect, engineer and musician, he aroused the wonder and admiration of his contemporaries. But to them, the studies which traversed the whole domain of Nature, prefiguring in their scope what the spirit of the Renaissance should afterwards become, were so imperfectly comprehended as to seem mere trifles, 'ghiribizzi', to be mentioned apologetically, if at all, as showing the wayward inconstancy of genius, and with regret on account of the time thus wasted which might have been spent on painting. Modern savants have resolved these trifles, and in so doing have estimated the value of Leonardo's discoveries and observations in the realms of exact science. They have acclaimed him as one of the greatest of savants : not in completed endeavour which of itself reached fruition, but in conjecture and prefigurement of what the progress of science has in course of centuries established. Such conjecture, moreover, was not grounded in fantasy, but was the harvest of a lifetime of study of natural phenomena, and of close analysis of their laws. Anatomist, mathematician, chemist, geologist, botanist, astronomer, geographer — the application of each of these titles is fully justified by the contents of his manuscripts at Milan, Paris, Windsor and London. To estimate aright the value of his researches in the various domains of science would require an almost encyclopaedic width of knowledge. 

In respect to these Leonardo himself in his manuscripts must be accounted his own best biographer, in spite of what may appear the enigmatic brevity of some of his statements and inferences. It is not possible to claim for him originality in discovery in all the points wherein his researches anticipated principles which were subsequently established. So incomplete is the record of the intellectual life of Milan under the Sforzas, which has survived the storms of invasion that subsequently broke upon the city, as to cause positive statement on this point to be wellnigh impossible; something, however, should be allowed for the results of his intercourse with those who were occupied in the same fields of research. We are told that at a later period he was the friend of Marc Antonio della Torre who held the Chair of Anatomy in the University of Pavia, and that they mutually assisted each other's studies. He was also the friend of Fra Luca Pacioli, the mathematician, and drew the diagrams for his De Divina Proportioned and iie two were companions for some time in the autumn and winter of 1499 after leaving Milan together at the time of the French invasion. Numerous references and notes which occur throughout the manuscripts show that he was indefatigable in seeking to acquire knowledge from every possible source, either by obtaining the loan of books or treatises, or by application to those interested in the same studies. From the astrologers then to be found at Ludovic's court — Ambrogio da Rosate and the others — he learnt nothing. He rated their wisdom on a par with that of the alchemists and the seekers after perpetual motion. His study of the heavens differed from theirs as much in method as in purpose. His instruments were scientific, and even at times suggestively modern. The line in the Codice Atlantico, 'construct glasses to see the moon large', (fa occhiali da vedere la luna grande) refers, however, only to the use of magnifying glasses; the invention of the telescope is to be assigned to the century following. 

At the commencement of the sixteenth century, the Ptolemaic theory of the Universe was still held in universal acceptance. Leonardo at first accepted it, and in his earlier writings the earth is represented as fixed, with the sun and moon revolving round it. He ended at some stage farther on in the path of modern discovery. On a page of mathematical notes at Windsor he has written in large letters, 'the sun does not 
move' (il sole no si muove). 

He has been spoken of as the forerunner of Francis Bacon, of James Watt, of Sir Isaac Newton, of William Harvey. He cannot be said to have anticipated the discoveries with which their names are associated. It may, however, be claimed that he anticipated the methods of investigation which, when pursued to their logical issue, could not but lead to these discoveries. 

The great anatomist Vesalius, after having given up his Chair of Anatomy in 1561 in order to become the court physician at Madrid, spoke of himself as still looking forward to studying 'that true bible as we count it of the human body and of the nature of man'. Sir Michael Foster takes these words as the keynote of the life-work of Vesalius: 'the true bible to read is nature itself, things as they are, not the printed pages of Galen or another; science comes by observation not by authority'. In method Leonardo was the forerunner of Vesalius, and consequently of William Harvey, whose great work was the outcome of Vesalius's teaching. No passage in his writings constitutes an anticipation of Harvey's discovery. He knew that the blood moved just as he also knew that the sun did not move, but the law of the circulation of the blood was as far beyond the stage at which his deductions had arrived as was the discovery of Copernicus. It was his work to establish, even before the birth of Vesalius, that 'science comes by observation not by authority'. Yet he was no mere empiric. He knew the authorities. He quotes in his manuscripts from Mundinus's Anatomia, and he must have known the work of Galen to which Mundinus served as an introduction. At a time when the Church 'taught the sacredness of the human corpse, and was ready to punish as a sacrilege the use of the anatomist's scalpel', Leonardo practised dissection; and he suffered in consequence of his temerity, since it was subsequent to the malicious laying of information concerning these experiments that the withdrawal of the papal favour brought about his departure from Rome in 1 51 5. Of such temerity the anatomical drawings are a rich harvest. The pall of authority was thrown aside; the primary need was for actual investigation, and of this they are a record. He would agree, he says, 
as to it being better for the student to watch a demonstration in anatomy than to see his drawings, 'if only it were possible to observe all the 
details shown in these drawings in a single figure; in which, with all your ability, you will not see nor acquire a knowledge of more than some few veins, while, in order to obtain an exact and complete knowledge of these, I have dissected more than ten human bodies, destroying all the various members and removing even the very smallest particles of the flesh which surrounded these veins, without causing any effusion of blood other than the imperceptible bleeding of the capillary veins'. 

It was after his examination of these drawings that the great anatomist Dr. William Hunter wrote that he was fully of opinion that 'Leonardo was the best Anatomist at that time in the world'. 

Coleridge called Shakespeare 'myriad-minded'. If the Baconian contention were established the result would afford a parallel to the myriad-mindedness of Leonardo. Morelli speaks of him as 'perhaps the most richly gifted by nature among all the sons of men'. Equally emphatic is the tribute of Francis I recorded by Benvenuto Cellini: 'He did not believe that any other man had come into the world who had attained so great knowledge as Leonardo, and that not only as sculptor, painter, and architect, for beyond that he was a profound philosopher.' 

In regard to this undefined, ungarnered knowledge, the prevalent note of the early biographers is frankly the marvellous. To us his personality seems to outspan the confines of his age, to project itself by the inherent force of its vitality down into modern times and so to take its due place among the intuitive influences of modern thought. To them, on the other hand, his personality projecting beyond the limits of his own age seemed to stretch back into the age of legend, to gather something of its insouciance and its mystery. The figure — never sufficiently to be extolled for beauty of person — wandering through princes' courts improvising songs, bearing a lute as a gift from one patron to another, and playing upon it in such skilled fashion that that alone out of all the arts of which he had knowledge would suffice as 'open sesame' to win him welcome, seems indeed rather to have its habitation in Provence at the close of the twelfth century than to be that of a contemporary and fellow-citizen of Machiavelli and Savonarola. In lieu of any such period of toilsome apprenticeship as Vasari's biographies lead us customarily to expect, there seems almost a Pallas-like maturity at birth. The angel painted by him when an apprentice causes his master to abandon the use of the brush, in chagrin that a mere child had surpassed him; and so, in like manner, we are told that a monster which he painted on a shield filled his own father with dismay. Unsatisfied with this mastery of the arts he sought to discern the arcana of Nature; and whither the quest had led him it was not for a mere biographer to say. But each will help us to conjecture, with hints more expressive than words, and less rebuttable. Leonardo's scornful references to the pretended wisdom of alchemists, astrologers and necromancers lay hidden meanwhile in the manuscripts, not available to contravene such suppositions. 

The personality as represented in the early biographies is substantially that which is expressed in the phrase of Michelet, 'Leonard, cefrere italien de Faust'. It tells of him that he chose rather to know than to be, and that curiosity led him within the forbidden portals. It represents in fact the popular medieval conception of scientific study. Much of the modern aesthetic appreciation is in its essential conception a more temperate restatement of the same point of view. Errors — or at any rate some of them! — are corrected in the light of the results of critical research from Amoretti downwards: the outlook, nevertheless, remains that of Vasari and the Anonimo Fiorentino. Ruskin's dictum, that 'he debased his finer instincts by caricature and remained to the end of his days the slave of an archaic smile', is at one with the opinion of the folk of Wittenberg who lamented Faust's use of the unhallowed arts which had made him Helen's lover. The true analogy lies not with Faust but with Goethe, between whom and Leonardo there is perhaps as great a psychological resemblance as ever has existed between two men of supreme genius. In each the purely artistic and creative faculties became subordinate, mastered by the sanity of the philosophical faculties. In each alike the restless workings of the human spirit desiring to know, ranged over the various mediums of artistic expression, tempered them to its uses, and finally passed on, looking beyond the art to the thought itself, unsatisfied with what — even in its perfection of utterance — was but a pale reflex of the phenomena it would observe. The two parts of Goethe's Faust-drama symbolize the gradual change of purpose, and may perhaps serve to represent Leonardo's two spheres of activity. Verrocchio's bottega and all the influences of the art-world of Florence in the Quattrocento were for him tutelage and training, as the medieval chap-book legends and the newly-arisen literature of the Romantic School were for the poet of Weimar. The result in each case was limpid, serene, majestic, for the elements which had gone to the making of it had been fused molten in the flame-heat of genius. Yet the man behind the artist is still unsatisfied. He never shares the artist's accomplishment with such measure of absorption as characterized Raphael and Giovanni Bellini. He has something of the aloofness of Faust. There is that within him which art's appeal to the senses never kindled into life, never impelled to utter to one of its moments the supreme shibboleth of Hedonism, 'Stay, thou art so fair'. All the allurements of the medieval chap-book legend were revealed in the first part of the Faust-drama; then, this invocation being as yet unuttered, 
the thinker essays the problem. No beaten footsteps as before in this new avenue of approach. No clear limpidity of ordered effort. Titanic energy struggles painfully amid the chaos of dimly-perceived primeval forces. The result — even the very effort itself — according to much critical opinion, was an artistic mistake. 

The same judgment was passed on Leonardo's work as philosopher and scientist by the earliest of his biographers. Yet in each case the thinker is nearer to the verities. Faust is regenerated by the service of man from out of the hell of medieval tradition. It was the cramping fetter of medieval tradition upon thought which Leonardo toiled to unloose. It was his aim to extend the limits of man's knowledge of himself, of his structure, of his environments, of all the forms of life around him, of the manner of the building up of the earth and sea, and of the firmament of the heavens. To this end he toiled at the patient exposition of natural things, steadfastly, and in proud confidence of purpose. 'I wish', he says, 'to work miracles : I may have fewer possessions than other men who are more tranquil and than those who wish to grow rich in a day.' 

Inchoate and comparatively barren of result as was his investigation of natural phenomena, it nevertheless was actual investigation, and it 
attained results. We may instance the passages in the manuscript formerly at Holkham Hall, in which the fact of fossil shells being found in the higher mountain ridges of Lombardy is used by a process of deductive reasoning to show how at one time the waters covered the earth. The hypo- thetical argument that the presence of these shells is to be attributed to the Flood, he meets by considering the rate of the cockel's progress. It is a creature possessed of no swifter power of motion when out of water than the snail. It cannot swim, but makes a furrow in the sand by means of its sides, and travels in this furrow a space of three to four braccia daily, and by such a method of progression it could not in forty days have travelled from the Adriatic to Monferrato in Lombardy, a distance of two hundred and fifty miles. Neither is it a case of dead 
shells having been carried there by the force of the waves, for the living are recognizable by the shells being in pairs. Many other passages in 
the manuscripts might be cited to show by what varied paths he anticipated the modern methods of scientific investigation. The words which 
Pater uses of the Renaissance of the fifteenth century, 'in many things great rather by what it designed or aspired to do than by what it ac- 
tually achieved' — applicable to Leonardo in respect of his work as an artist — are no whit the less applicable in reference to his work in sci- 
ence. Painting and sculpture filled only two of the facets of a mind which, as a crystal, took the light from whatever quarter light came. 

As, however, it was in these arts that he accomplished most, so such of his writings as treat of them are on the whole the most practical. In 
science, for the most part he heralded the work of others : in respect of his writings on art, we may apply to him the words which Diirer uses 
of himself in a similar connection : 'what he set down with the pen he did with the hand'. It is this very factor of experience working in the 
mind which at times causes an abrupt antithesis, in the transition from the general principle to discussion of the means whereby it should be 
realized. His work may perhaps be considered to lose somewhat of its literary value in consequence, but it acquires an almost unique interest 
among treatises on art by its combination of the two standpoints of theory and practice. Of this, one of the most striking instances occurs 
in a passage which is only to be found in the recension of the treatise on 'Painting' in the Vatican (Ludwig, cap. 180). Leonardo there sums 
up, tritely and profoundly, what should be the painter's purpose: 'a good painter has two chief objects to paint, man and the intention of 
his soul; the former is easy the latter hard'; after which follows the eminently reasonable, if perhaps unexpected, explanation, 'because he 
has to represent it by the attitudes and movements of the limbs'; and the knowledge of these, he proceeds to say, should be acquired by ob- 
serving the dumb, because their movements are more natural than those of any other class of persons. This very practical direction how to approach towards the realization of an apparently abstract aim is entirely characteristic of his intention. The supreme misfortune, he says, 
is when theory outstrips performance. This essential practicality of mind brought about the result that in the more abstract portions of this 
branch of his writings his zest for first principles is most apparent. The sun, the origin of light and shade, is recognized as the first artist, and 
we are told that 'the first picture consisted merely in a line which surrounded the shadow of a man cast by the sun upon a wall'; and the 
comparison of poetry and painting resolves itself into a consideration of the relative importance of the senses to which the two arts make their 
appeal. 

It is perhaps in the passages indicating the manner in which particular scenes and actions should be represented in art that Leonardo's 
powers as a writer find their most impressive utterance. His natural inclination impelled him to the contemplation of the vast and awe-inspir- 
ing in Nature; but in these terse, vivid, analytic descriptions, the consideration of the ultimate purpose operates throughout to restrain 
and co-ordinate. The descriptive passage entitled 'The way to represent a battle', in which the effect is built up entirely by fidelity of de- 
tail, forms an absolute triumph of realism. There can be no possibility of difference of opinion as to how Leonardo regarded warfare. It was a 
grim necessity, and he was himself busied on occasions in devising its instruments; but he had no illusions as to its real nature, he characterizes it elsewhere as 'most bestial madness' (bestialissima pazzia) . Here, however, he never suffers his pen to digress from the work of simple description. To generalize would be alien to his purpose, which is to show how to portray a battle in progress. Consequently he shows what it is that is actually happening amid the clouds of dust and smoke and the rain of gunshot and falling arrows; and describes tersely, graph- 
ically, relentlessly, the passions and agonies of the combatants as shown in their faces and their actions, the bitterness of the deaths of the van- 
quished, the fury and exhaustion of the victors and the mad terror of the horses, since these should find a place in the work of whosoever 
would represent war; 'and see to it', he says in conclusion, 'that you make no level spot of ground that is not trampled over with blood'. The passage enables us in part to realize what he sets himself to represent in the picture of the Battle of Anghiari. It is, however, far more than a mere note for a picture. It possesses an interest and value apart either from this fact or from the mastery in the art of writing which it reveals. Its ultimate value is moral and didactic. He forbears to generalize but constrains the reader in his stead. His description is of the identical spirit which has animated the creations of Tolstoy and Verestchagin. Like these, Leonardo seeks to make war impossible, by showing it stripped of all its pageantry and trappings, in its naked and hideous reality. 

The passages which describe a tempest and a deluge, and their representation in painting, possess the same vigorous realism and fidelity of 
detail, and contain some of Leonardo's most eloquent and picturesque writing; and among the other notes connected with pictures we may 
instance that for the 'Last Supper', descriptive of the actions of the disciples, which, although of far slighter mould than any of the pas- 
sages already referred to, yet possesses a restrained but very distinct dramatic power. These same qualities may be discerned perhaps even 
to more advantage in one of the very rare comments on public events which are to be found in his writings. After Ludovic Sforza's attempt 
to regain possession of Lombardy had ended with his defeat and capture at the battle of Novara in April 1500, Leonardo wrote among 
notes on various matters, 'The Duke has lost his State, his possessions, and his liberty, and he has seen none of his works finished'. (II Duce 
perse lo Stato e la roba e la liberta, e nessuna sua opera si fini per lui.) Leonardo was a homeless wanderer in consequence of the events re- 
ferred to, and one of the works of which the Duke had not witnessed the completion was that of the statue on which Leonardo had been en- 
gaged intermittently during sixteen years, and the model of which had served as a target for the French soldiery; but this terse impassive com- 
ment is the only reference to these occurrences found in his writings. There is a certain poignant brevity and concentration in the sentence, 
which suffices even to recall some of the most inevitable lines of Dante. It is within the narrow limits of the short sentence and the apothegm 
that Leonardo's command of language is most luminous. In some of these the thought expressed is so wedded to the words as scarcely to 
suffer transference. 'Si come una giornata bene spesa da lieto dormire cosi una vita bene usata da lieto morire' must lose something of its 
grace in any rendering. Certain of these sentences record the phenomena of Nature so simply as to cause us almost to doubt whether they 
are intended to do more than this. 'All the flowers which see the sun mature their seed, and not the others, that is those which see only the 
reflection of the sun', is perhaps written as an observation of Nature without thought of a deeper meaning; but it is hard to suppose that a 
similar restriction applies to the sentence: 'tears come from the heart not from the brain'; although it is found in a manuscript which treats 
of anatomy. 

It would seem that it was natural to him as a writer to use words as symbols and figuratively, thus employing things evident and revealed 
in metaphor. Of this habit of veiled utterance the section of his imaginative writings known as 'the Prophecies' affords the most impressive 
and sustained series of instances. Some few of these are, as their name implies, a forecast of future conditions; many attack the vices and 
abuses of his own time. In the succinct, antithetical form of their composition Leonardo apparently created his own model. 

There are questions more intimate than any of those which arise from the consideration of his achievement in these various arts and 
sciences; questions which the mere number of these external interests tends to veil in comparative obscurity, causing us to regard Leonardo 
almost as a resultant of forces rather than as an individual, to see in him as it were an embodiment of the various intellectual tendencies of 
the Renaissance — as though the achievements were the man. The figure crosses the stage of life in triumph, playing to perfection many parts. 
But of these enough. Let us try to come nearer, to get past the cloak of his activities, and essay to 'pluck the heart out of this mystery'. As a 
means towards this end, let us consider his attitude with regard to certain of the problems of life. 

His writings inculcate the highest morality, though rather as a reasoned process of the mind than as a revelation from an external authority. He preserves so complete a reticence on the subject of doctrinal belief as to leave very little base for inference as to his faith or lack of faith. The statement of Vasari, that he did not conform to any religion, deeming it better perhaps to be a philosopher than a Christian, was omitted in the second edition of the Lives, and may therefore be looked upon as probably merely a crystallization of some piece of Florentine gossip. It would be idle to attempt to surmise as to the reason of the withdrawal. To whatever cause this may have been due, its significance is no whit the less as outweighing a mass of suggestion and vain repetition on this subject by later writers. In temperament Leonardo has something akin to certain of the precursors of the Reformation. In any conflict between the dictates of reason and of authority he would be found on the side of freedom of thought. 'Whoever', he wrote, 'in discussion adduces authority uses not his intellect but rather memory.' 

The cast of his mind was anti-clerical. His indignation at the abuses and corruption of the Church found expression in satire as direct and piercing as that of Erasmus. His scorn of the vices of the priesthood, of their encouragement of superstition, of the trade in miracles and pardons, which is eloquently expressed in the section of his writings known as 'the Prophecies', may not unnaturally have earned for him the title of heretic from those whom he attacked. His quarrel lay, however, not with the foundations on which faith rested, but with what he conceived to be its degradation in practice by its votaries. His own path lay along the field of scientific inquiry; but where the results of this research seemed at variance with revealed truth, he would reserve the issue, disclaiming the suggestion of antagonism. Nature indeed cannot break her own laws. The processes of science are sure, but there are regions where we cannot follow them. 'Our body is subject to heaven, and heaven is subject to the spirit.' So at the conclusion of a passage describing the natural origin of life, he adds, 'I speak not against the sacred books, for they are supreme truth'. The words seem a protest against the sterile discussion of these things. There is, indeed, a reticence in the expression of the formulas of faith, but the strands of its presence may be seen in the web of life. 

The impelling necessity to use life fully is the ever-recurrent burden of his moral sayings: 

'Life well spent is long.' 

'Thou, O God, dost sell unto us all good things at the price of labour.' 

'As a well-spent day brings happy sleep, so life well used brings happy death.' 

This vision of the end is steadfast. Death follows life even as sleep rounds ofr" the day, and as we work well in the day, so sleep when it comes is happy and untroubled. During the passing of the day there is so much to be done, such opportunity to construct and to observe, so much knowledge to be won about this world wherein the day is passed, that there is scarce time remaining in which to stand in fear and wonder at thought of what chimeras the coming shadow may hold within it. It is better to use to-day than to spend it by questioning of tomorrow. Duty in life is clear and we must follow it. When he speaks of what comes after, it is with that hesitance common to all, unless to speak of it be made habituate by custom, for to all, whatever be their belief, there yet remains something unknowable in the conditions of the change. 

In one of the most beautiful passages of his writings — a fragment on time, the destroyer — Leonardo describes Helen in her old age as look- 
ing into her mirror and seeing there the wrinkles which time had imprinted on her face, and then weeping, and wondering why she had been twice carried away. Beautiful as is the description the hand which penned it is pre-eminently that of the scientist; we seem to see the anatomist at work with the scalpel, so minute is the observation therein revealed as effect of age and of the relentless approach of death upon the human frame. 

'In her the painter had anatomized Time's ruin.' 

And yet, as modern erudition in the person of the late Gerolamo Calvi has recently shown, Leonardo was not the original author of the passage. He amplified it and transformed it into a richer harmony by placing the apostrophe to Time the destroyer at the beginning as well as at the end, but the description of Helen he found in Ovid's Metamorphoses (Book xv, 11. 232-6). 

The fact illustrates the difficulty of interpreting the contents of the Notebooks. They contain matter some of it unoriginal and some of this doubtless is as yet unidentified. 

The frequent recurrence in his writings and in his drawings and grotesques of the physical tokens of decay and death argues no morbid predilection, such as that shown by the painters of the danse macabre. It forms a proportioned part of his study and 'patient exposition' of 
the origin and development of the whole structure of man. In the results as we may read them, there is no incursion of the personal note. His attitude is always that of an observer, looking with curious eyes, noting all the phenomena of physical change, but yet all the while presrerving a strange impassivity. He never in any of his works or in his manuscripts gives the suggestion of possessing any of that regret at the passing of time which rings through Giorgione's sun-steeped idylls. Indeed, from all such lament he expressly dissociates himself. Time, he maintains, stays long enough for those who use it. The mere fact of the inevitability of death forbids regret. It therefore cannot be an evil. He speaks of it as taking away the memory of evil, and compares it with the sleep which follows after the day. The thought of this sleep brings silence: when on rare occasion the silence is broken, he stands with Shakespeare and Montaigne, revealing, as they do, when they address themselves to the same question, a quiet confidence, serene and proud. 

The author of Virginibus Puerisque, discoursing whimsically upon the incidence and attributes of the tender passion, professes his utter inability to comprehend how any member of his own sex, with at most two exceptions, can ever have been found worthy to be its object. 'It might be very well', he says, 'if the Apollo Belvedere should suddenly glow all over into life, and step forward from the pedestal with that god-like air of his. But of the misbegotten changelings who call themselves men and prate intolerably over dinner-tables, I never saw one who seemed worthy to inspire love — no, nor read of any except Leonardo da Vinci and perhaps Goethe in his youth.' 

The suggestion as to the Apollo Belvedere is in entire harmony with the association of the names which follow. For if it had ever come to pass, as is conjectured in Heine's fantasy, that the gods of Greece, after their worship ceased, fallen on days of adversity, and constrained to baser uses, had walked the earth as men, surely no lives whereof record holds had come more naturally to Apollo's lot than would those of Goethe and Leonardo. 

It would be vain to attempt to find better instances, yet these give only a capricious support at best to Stevenson's contention. They afford far more proof of his amazing temerity in attempting to view the kingdom of sentiment from the feminine standpoint. 

These two names he ranks together in isolation from the rest of their sex — and this in respect precisely of that condition wherein the records 
of their lives reveal the least resemblance. Goethe was as susceptible and almost as fickle as Jupiter himself. The story of his heart is a romance with many chapters, each enshrining a new name, and all ending abruptly at the stage at which the poet remembers— at times somewhat tardily — the paramount claims of his art. 

But in the case of Leonardo there are no grounds for supposing that any one such chapter was ever begun. None of his biographers connect his name with that of any woman in the way of love, nor do his own writings afford any such indication. They show that he lived only for the things of the mind. He would seem to have renounced deliberately all thought of participation in the tenderness of human relationship. He looked upon it as alien to the artist's supreme purpose: he must needs be solitary in order to live entirely for his art. His conception of the mental conditions requisite for the production of great art presupposes something of that isolation expressed in Pater's phrase: 'each mind keeping as a solitary prisoner its own dream of a world'. 

The praise of solitude has ever been a fecund theme, although much of the fervour of its votaries has resulted in little more than a reverber- ation of the monkish jingle, 'O beata solitudo, O sola beatitudo.' In so far as praise of solitude is dispraise of the world and one's fellow-men and the expression of desire to shun them and their activities, it is a sterile thing and worse. Solitude is unnatural and only the use of it can justify the condition. Maybe that even then the dream will never come to birth! Certain it is that if it does we must suffer the pangs alone! Concentration of the mind comes by solitude; and in this, according to Leonardo, its value to the artist consists. (Se tu sarai solo tu sarai tutto tuo.) 'If you are alone you belong entirely to yourself. If you are accompanied even by one companion you belong only half to yourself, or even less in proportion to the thoughtlessness of his conduct. ... If you must have companionship choose it from your studio; it may then help you to obtain the advantages which result from different methods of study.' Such companionship of the studio implies some such measure of equality of attainment as it can never have been his own lot to meet with after leaving the circle of Verrocchio and the art world of Florence. His own lesser companions of the studio were his pupils and servants, and the only one of these whom he admitted to any degree of personal intimacy was Francesco de' Melzi, who seems to have stood to him in the concluding years of his life almost in the position of a son to a father. 

Behind all his strength lay springs of tenderness; in life confined within the strait limits whereby his spirit proposed that its work should be more surely done, in his art they are manifest, therein revealing the repression of his life. His pictures are now so few that it would be to his drawings that we should chiefly look for support of this statement, and of these primarily perhaps to the many studies for Madonna pictures, and the sketches of children made in connection with them; also, however, to the two versions of the composition of the Madonna and Child with St. Anne. The differences between that in Burlington House and that in the Louvre show the artist's gradual growth of purpose. One motive, however, is found in both, namely that the Madonna is represented as so entirely absorbed in her Child that she is entirely unconscious of aught else. With the exception of the Madonna della Seggiola, and perhaps certain others of Raphael's Madonnas, there is no Madonna picture in Italian art in which the conception is more human or the ecstasy of motherhood is rendered with greater tenderness. So Tart console de la vie'; and the same may be said in Leonardo's case of Nature perhaps even more truly than of art. If indeed any thought of consolation can be suffered in connection with a life so confident and full! For man's work is his ultimate self. Such human hopes as begin and end in the individual are puny even in their 
highest fulfilment, and the processes of Nature, whatever their final end, seem eternal in contrast with their transience. 

He interpreted man's highest aim to consist in seeking to know and to hand on the lamp of knowledge.