"In the opening lines of the volume of manuscript notes 'begun at Florence in the house of Piero di Braccio Martelli, on the 22nd day of March, 1508', now in the British Museum (Arundel MSS. 263), Leonardo explains the method of its composition. The passage may serve to summarize the impression made by the whole mass of Leonardo's manuscripts. 'This', he says, 'will be a collection without order, made up of many sheets which I have copied here, hoping afterwards to arrange them in order in their proper places according to the subjects of which they treat; and I believe that before I am at the end of this I shall have to repeat the same thing several times; and therefore, O reader, blame me not, because the subjects are many, and the memory cannot retain them and say "this I will not write because I have already written it". And if I wished to avoid falling into this mistake it would be necessary, in order to prevent repetition, that on every occasion when I wished to transcribe a passage I should always read over all the preceding portion, and this especially because long periods of time elapse between one time of writing and another.' Certain pages in the volume of manuscript in the British Museum would indeed seem to be of a much earlier date than this introductory sentence, and the whole body of the manuscripts, as may be shown by the time-references contained in them, extend over a period of some forty years, from Leonardo's early manhood to his old age. He commenced them during the time of his first residence in Florence, and was still adding to them when at Amboise. 

The contents of this 'collection without order' are so diversified as to render wellnigh impossible any attempt at formal classification. In addition to the numerous fragments of letters, the personal records, the notes relating to his work as an artist, and the fragments of imaginative composition which are to be found therein, it presents by far the most complete record of his mental activity, and this may be said without exaggeration to have extended into practically all the avenues of human knowledge. These manuscripts serve in a sense to show the mind in its workshop, busied in researching, in making conjecture, and in recording phenomena, tempering to its uses, in so far as human instru 
ment may, the vast forces of Nature. He projected many treatises which should embody the results of these researches. Notes in the manuscripts themselves record the various stages of their composition. Some still exist in a more or less complete form. Of the fragments of others the order of arrangement is now only a matter of conjecture. In the manuscripts at Windsor, which treat mainly of anatomy, a note, dated April 2nd, 1489, speaks of writing the book 'about the human figure'. The manuscript given to the Ambrosian Library by Cardinal Federico Borromeo, now MS. C of the Institut de France, which is a treatise on light and shade, contains a note that 'on the 23rd day of April 1490, I commenced this book and recommenced the horse' — the latter reference being to the equestrian statue of Francesco Sforza. In August 1499 a note in the Codice At- 
lantico states that he was then writing 'upon movement and weight'. These dates are, however, of relatively less importance, because each of these subjects occupied his thoughts during a long period of years. The two first formed a part of the artist's complete equipment as Leonardo conceived it: the third found practical issue in his undertakings in canalization and engineering in Lombardy, Tuscany, Romagna and elsewhere. In connection with the former of these two divisions of his activities may be cited the treatise on the nature of water formerly in the possession of the Earl of Leicester, and the sarrtf subject is also treated of among others in MS. F of the Institut, which according to a note, was commenced at Milan on September 12th, 1508. 

The manuscripts as a whole are picturesquely described in the diary of a certain Antonio de Beatis, the secretary of the Cardinal of Aragon, who with his patron visited Leonardo at Amboise in October 1517. The many wanderings of the painter's life were then ended, and he was living with Francesco Melzi and his servant Battista de Villanis in the manor house of Cloux, the gift of Francis I. The diary relates that he showed his guests three pictures, the St. John, the Madonna with St. Anne, and the portrait of a Florentine lady, painted at the request of Giuliano de' Medici, which cannot now be identified. It further states that paralysis had attacked his right hand, and that therefore he could no longer paint with such weetness as formerly, but still occupied himself in making drawings and giving instruction to others. (May the inference be that he then drew with the left hand? If so he presumably used it in the manuscripts, which are written backwards.) 

'This gentleman has', he continues, 'written of anatomy with such detail, showing by illustrations the limbs, muscles, nerves, veins, ligaments, intestines and whatever else there is to discuss in the bodies of men and women, in a way that has never yet been done by anyone else. All this we have seen with our own eyes; and he said that he had dissected more than thirty bodies, both of men and women, of all ages. He has also written of the nature of water, of divers machines and of other matters, which he has set down in an infinite number of volumes all in the vulgar tongue, which if they should be published will be profitable and very enjoyable.' 

This description of the manuscripts — the only one by an eyewitness during Leonardo's lifetime — leads to the supposition that, if not all, at any rate by far the greater part of them were in Leonardo's possession at the time that he went to France, and were at Cloux at the time of his death. 

The manuscripts then passed into the possession of Francesco Melzi, to whom Leonardo in his will, dated April 23rd, 151 8, bequeathed 'in return for the services and favours done him in the past', 'each and all of the books of which the said Testator is at present possessed, together with the other instruments and portraits which belong to his art and calling as a Painter'. Melzi returned to Milan shortly after Leonardo's death and took the manuscripts with him, and four years later a certain Alberto Bendedeo, writing from Milan to Alfonso d'Este, said that he believed that the Melzi whom Leonardo made his heir was in possession of 'such of his notebooks as treated of anatomy and many other beautiful things'. 

Vasari visited Milan in 1566, and he states that Melzi whom he saw, and who was then 'a beautiful and gentle old man', possessed a great part of Leonardo's papers of the anatomy of the human body, and kept them with as much care as though they were relics. Some of the manuscripts had already at this time passed into other hands, for Vasari refers to some which treated of painting and methods of drawing and colouring as being then in the possession of a certain Milanese painter whose name he does not mention. The care which had been taken of those in Melzi's possession ceased at his death, which occurred in 1570. Some years later no restriction was placed by Melzi's heirs upon the action of a certain Lelio Gavardi di Asola, a tutor in the Melzi family, who took thirteen of the volumes of manuscripts with him to Florence for the purpose of disposing of them to the Grand Duke, Francesco. The duke's death, however, prevented the realization of this project, and Gavardi subsequently took the volumes with him to Pisa. Giovanni Ambrogio Mazzenta, a Milanese who was then at the University of Pisa studying law, remonstrated with Gavardi upon his conduct, and with such success that on Mazzenta's return to Milan in 1587 he took the volumes with him for the purpose of restoring them to the Melzi family. When, however, he attempted to perform this duty Dr. Orazio Melzi was so astonished at his solicitude in the matter that he made him a present of all the thirteen volumes, telling him further that there were many other drawings by Leonardo lying uncared-for in the attics of his villa at Vaprio. In 1590 Giovanni Ambrogio Mazzenta joined the Barnabite Order and the volumes were then given 
by him to his brothers. They seemed to have talked somewhat freely about the incident, and in consequence, according to Ambrogio Mazzenta's account, many people were filled with the desire to obtain similar treasures, and Orazio Melzi gave away freely drawings, clay models, anatomical studies, and other precious relics from Leonardo's studio. 

Among the others who thus came into possession of works by Leonardo was the sculptor Pompeo Leoni, who was employed in the service of the King of Spain. He afterwards induced Orazio Melzi, by the promise of obtaining for him official honours and preferment, to appeal to Guido Mazzenta, in whose possession they then were, to restore the volumes of Leonardo's manuscripts so that he might be enabled to present them to Philip II. Melzi's entreaties were successful in obtaining the return of seven volumes, and three of the others subsequently passed into Pompeo Leoni's possession on the death of one of the Mazzentas. Of the remaining three, one according to Mazzenta's account was given to the Cardinal Federico Borromeo, and passed into the Ambrosian Library which he founded in 1603; another was given to the painter Ambrogio Figini, who afterwards bequeathed it to Ercole Bianchi; it was subsequently in the po c session of Joseph Smith, English Consul at Venice, and with the sale of his effects in 175c) all record of it ends; the third was given to Charles Emmanuel, Duke of Savoy, and nothing further is known as to its history. Pro- fessor Govi has conjectured that it was perhaps burnt in one of the fires which occurred in the Royal Library at Turin in 1667 or 1679. 

Some of the volumes of the manuscripts which had passed into the possession of Pompeo Leoni were afterwards cut in pieces by him in order to form one large volume from the leaves, together with some of the drawings which he had obtained from Melzi's villa at Vaprio. This volume, known as the Codice Atlantico on account of its size, contains four hundred and two sheets and more than seventeen hundred drawings, and bears on its cover the inscription: 








Apparently the collector's instinct proved stronger in Pompeo Leoni than his original intention. He was subsequently in Madrid, where he was engaged in executing bronzes for the royal tombs in the Escurial, but there is no evidence to show that he ever parted with any of Leonardo's manuscripts to Philip II. The Codice Atlantico remained in his possession until his death in 1610, and then passed to his heir, Polidoro Calchi, y whom it was sold in 1625 to Count Galeazzo Arconati. Two of Leonardo's manuscripts in Pompeo Leoni's possession were included among his effects sold after his death at Madrid, and were then bought by Don Juan de Espina. It would seem probable that others of the manuscripts in Pompeo Leoni's possession descended to his heir Calchi, and from him passed into the possession of Count Arconati, because the latter in 1636 presented twelve volumes of Leonardo's manuscripts to the Ambrosian Library at Milan. The volume which Mazzenta had given to Cardinal Federico Borromeo had already been placed there in 1603, and in 1674 yet another volume of Leonardo's manuscripts was added by the gift of Count Orazio Archinti. 

Of the list of twelve manuscripts as described in Count Archonati's deed of gift to the Ambrosian Library, the second was afterwards lost, and the fifth was removed from the Library — it being, as the description shows, identical with the manuscript of Leonardo's which in about the year 1750 was bought from a certain Gaetano Caccia of Novara by Carlo Trivulzio and is now in the possession of Prince Trivulzio at Milan. The remaining ten manuscripts of the Arconati donation, together with the two from Cardinal Federico Borromeo and Count Archinti respectively, were in the Ambrosian Library until 1796. There was then also with them a manuscript of ten sheets which treated of the eye, the provenance of which is unknown, but which it is conjectured had been substituted for the manuscript now in the collection of Prince Trivulzio. These thirteen manuscripts were all removed to Paris in the year 1796 in pursuance of the decree of Bonaparte as General-in-Chief of the Army of Italy of 30 Floreal An. IV (May 19th, 1796), providing for the appointment of an agent who should select such pictures and other works of art as might be worthy of transmission to France. The words of the decree authorizing and justifying the removal arrest attention by the naivety of their i$ptS. 'All men of genius', it ran, 'all who have attained distinction in the republic of letters are French, whatever be the country which has given them birth'. 
(Tous les hommes de genie, tous ceux qui ont obtenu un rang distingue dans la republique des lettres, sont Francais, quelque soit le pays 
qui les ait vus naitre.) 

The Codice Atlantico was in the Bibliotheque Nationale at Paris in August 1796. The other twelve volumes of the manuscripts were deposited in the Institut de France. In 1815 the Austrian Ambassador, as representing Lombardy, made application for the return of all the Leonardo manuscripts. The request was complied with as regards the Codice Atlantico, which was then restored to the Ambrosian Library at Milan, but the twelve volumes in the library of the Institut de France were apparently overlooked, and there they have since remained. 

On their arrival in France the manuscripts were described by J. B. Venturi, who then marked them with the lettering whereby they have subsequently been distinguished. He gave their total number as fourteen, because MS. B contained an appendix of eighteen pages which 
could be separated and considered as the fourteenth volume. 

This manuscript is identical with No. 3 in the Arconati donation, which is described as having at the end a small 'volumetto' of eighteen pages containing various mathematical figures and drawings of birds. This 'volumetto' seems in fact to have been treated somewhat as Venturi suggests by Count Guglielmo Libri, who frequently had access to the manuscripts in the Institut de France in the early part of last century, and who apparently abstracted it at some time previous to 1848, at which date its loss was discovered. In 1868 it was sold by Libri to Count Giacomo Manzoni of Lugo, and in 1892 it was acquired from Count Manzoni's heirs by M. SabachnikofT, by whom it was published in the following year as 11 Codice sul Volo degli Uccelli (edit. Piumati e SabachnikofT, Paris, 1893). It has subsequently been presented to the Royal Library at Turin. 

Two other manuscripts by Leonardo, of sixty-eight and twenty-six pages respectively, now in the Bibliotheque Nationale (Nos. 2038 and 2037), must have originally formed part of the manuscripts A and B of the Institut de France. They tally both in the dimensions of the pages and in the subjects of which they treat, and their total numbers added to those of Manuscripts A and B respectively do not amount to quite the full numbers of the leaves which these two manuscripts possessed in 1636, as described in the list of the Arconati donation. 

These two manuscripts in the Bibliotheque Nationale were formerly in the collection of the late Earl of Ashburnham, who purchased them in 1875 from Count Libri, from whom, as we have seen, Count Manzoni had purchased the 'volumetto' 'On the flight of birds'. The mutilation of Manuscripts A and B of the Institut de France and the removal of the 'volumetto' were first discovered in the year 1848. It is impossible to avoid the inference that the action in each case was the work of Count Libri. The two manuscripts of the Bibliotheque Nationale have been included in the edition of the manuscripts of the Institut de France published in facsimile, with a transcript and French translation by M. Ravaisson-Mollien, in six volumes (Paris, 1880-91). 

The Codice Atlantico has also been published in facsimile, with a transcript, under the direction of the Accademia dei Lincei, at Rome(1894-1904); and the manuscript in the possession of Prince Trivulzio, which as we have seen was formerly in the Ambrosian Library as one of the Arconati bequest, has been published in facsimile with a transcript by Signor Beltrami (Milan, 1892). 

We may now consider the Arconati bequest from another standpoint. The count's munificence was commemorated in the following inscription which was set in marble on the wall of the staircase of the Ambrosian Library: 




















'The glorious (boasting) inscription' — so described in the Memoirs of John Evelyn — has naturally attracted the attention of English travellers. Evelyn records his failure to obtain a sight of the manuscripts when he visited Milan in 1646, owing to the keeper of them being away and having taken the keys, but he states that he had been informed by the Lord Marshal, the Earl of Arundel, that all of them were small except one book, a huge folio containing four hundred leaves 'full of scratches of Indians', and 'whereas', he says, 'the inscription pretends that our King Charles had offered ^1000 for them, my lord himself told me that it was he who treated with Galeazzo for himself in the name and by the permission of the King, and that the Duke of Feria, who was then Governor, should make the bargain: but my lord having seen them since did not think them of so much worth'. The inscription, however, does not mention the name of the King. Addison, in his Remarks on Several Parts of Italy in describing his visit to Milan in 1701, mentions the Ambrosian Library as containing 'a manuscript of Leonardus Vincius, wich King James I could not procure, tho' he profer'd for it three thousand Spanish pistoles'; and the monarch in question is also stated to have been James I in the fuller record of the 
Arconati donation. The Duke of Feria was Governor of Milan from 1610 to 1633, during a part of the reign of both monarchs. Apparently, however, the manuscripts only passed into the possession cf Count Arconati in 1625, the year of the death of James I, and this renders it probable that the monarch referred to was Charles I. But the question of under which king has relatively little import, and with regard to the inscription, it may perhaps be well to recall the dictum of Dr. Johnson that 'in lapidary inscriptions a man is not upon oath'. The only inference that can fairly be drawn from the present instance is that the manuscripts by Leonardo now in the Royal Collection at Windsor did not form part of the Arconati Collection. This is also confirmed by the testimony of Lord Arundel, as recounted by Evelyn. That some of the Leonardo manuscripts at Windsor were once in the possession of Lord Arundel is established by the fact of the existence of an engraving of one of the drawings by Hollar, whom Lord Arundel brought from Prague and established in London. It is inscribed Leonardus da Vinci sic olim delineavit. W. Hollar fecit ex collectione 

That some of these Windsor manuscripts were also formerly in the Collection of Pompeo Leoni is clearly shown by the fact that one of the volumes is inscribed 'Disegni di Leonardo da Vinci Restaurati da Pompeo Leoni'. 

Two of the manuscripts in Pompeo Leoni's collection, as already stated, were purchased in Madrid after his death by Don Juan de Espina; and Mr. Alfred Marks — from whose important contributions to this branch of the subject in the Athenaeum of February 23rd and July 6th, 1878, many of the foregoing facts are derived — has shown that for one at any rate of these volumes, the Earl of Arundel was in treaty with Don Juan de Espina. The evidence of this is to be found in a note by Endymion Porter, of the date 1629, printed by Mr. Sainsbury in his Original Unpublished Papers illustrative of the Life of Rubens: '. . . of such things as my Lord Embassador S r Francis Cottington is to send out of Spain for my Lord of Arondell; and not to forget the booke of drawings of Leonardo de Vinze w ch is in Don Juan de Espinas hands' (p. 294). Don Juan seems for a time to have 
proved obdurate, for Lord Arundel wrote on January 19th, 1636, to Lord Aston, who was then ambassador to Spain: 'I beseech y u be mindfull of D. Jhon de Spinas booke, if his foolish humour change' (p. 299). There the record breaks ofT. But as Mr. Marks truly observes, there can be little doubt that eventually a change did take place in Don Juan's 'foolish humour'. At whatever date this happened the volume passed into Lord Arundel's possession. The earl may either have been negotiating for himself or for the King. If the former was the case, the book may presumably have passed into the Royal Collection at any time after 1646, when on the death of Lord Arundel his collections were partially dispersed. If it was not acquired previously the volume may have been bought in Holland by an agent of Charles II. 

The earliest record of any of Leonardo's manuscripts or drawings as being in the royal possession occurs in an inventory found by Richter in the Manuscript Department of the British Museum, which states that some drawings of Leonardo da Vinci, marked with a cross, were delivered for Her Majesty's use in the year 1728. 

Richter also cites a note in an inventory at Windsor Castle written at the beginning of last century, in which a drawing of Leonardo's is referred to as not having been in the volume compiled by Pompeo Leoni, but in one of the volumes in the Buonfigluolo Collection bought at Venice. Nothing apparently is known about the collection here referred to, but the note is important as tending to prove that the manuscripts by Leonardo now at Windsor were not all acquired at the same time, and did not all form part of Pompeo Leoni's collection. 

The volume of manuscript now in the British Museum (Arundel MSS. 263) was certainly once in the possession of Lord Arundel. Nothing is known of its history previous to this, and whether or no it belonged to Pompeo Leoni, or was acquired by purchase from Don Juan de Espina, it would be idle to attempt to conjecture. Lord Arundel had numerous agents in various parts of Europe, who were employed in collecting antiquities and works of art. It may, however, be noted that the greater part of his collection of manuscripts was acquired by the earl himself at Nuremberg in 1636, and had formerly belonged to Wilibald Pirkheimer, the humanist, the friend of Erasmus and Diirer. If any opportunity presented itself to him, Pirkheimer would certainly have possessed himself of any manuscript of Leonardo's; but to suppose him to have done so would be to assume that some of the manuscripts passed into other hands during Leonardo's lifetime, and this, though by no means impossible, is at any rate improbable. 

The only other manuscripts by Leonardo now known to exist, with the exception of a few separate sheets of sketches and diagrams with explanatory text, are three small notebooks in the Forster Library at South Kensington, and a volume of seventy-two pages long in the possession of the Earls of Leicester at Holkham Hall but recently sold to Mr. Pierpont Morgan and believed to be now in New York. The former were acquired in Vienna for a small sum by the first Earl of Lytton and by him presented to Mr. Forster; the latter, according to a note on the title-page, once belonged to the painter Giuseppe Ghezzi, who was living in Rome at the beginning of the eighteenth century, it having presumably been acquired by the first (Holkham) Earl of Leicester, who spent some years in Rome previous to 1775, and there acquired many art treasures. Its previous history is unknown. This volume — a treatise on the nature of water — is in all probability that referred to by Rafaelle du Fresne in the sketch of Leonardo's life which appears in his edition of the Trattato della Pittura, published in Paris in 1651, where it is stated that 'the undertaking of the canal of the Martesana was the occasion of his writing a book on the nature, weight, and motion of water, full of a great number of drawings of various wheels and engines for mills to regulate the flow of water and raise it to a height'. 

Of the manuscripts at Windsor which in the main are those that treat of anatomy, two volumes with facsimiles (60 leaves with about 400 drawings), transcripts and translations, have been issued by Messrs. Piumati and Sabachnikoff, Dell' Anatomia Fogli A (Paris, 1898), Fogli B (Turin, 1901), and the Quaderni d' Anatomia, six volumes (129 leaves with about 1050 drawings), by Messrs. Vangenstan, Fonahn and Hopstock (Oslo, 1911-16). Facsimiles of other leaves at Windsor were issued by Rouveyre from plates prepared for the use of Sabachnikoff. The manuscript in the British Museum and the three in the Forster Library were published in Rome by the Reale Commissione Vinciana at various dates from 1923-34, and an edition of the Leicester manuscript has been edited by Gerolamo Calvi (Milan, 1909). 

As Leonardo's fame as a writer has chiefly rested upon the Treatise on Painting, it may not be out of place here to attempt to state the relation which this work bears to the original manuscripts. 

The Treatise was first published by Rafaelle du Fresne, in Paris, in 1651, a French translation by Roland Freard, sieur de Chambrai, being also issued in the same year. Du Fresne derived his text from two old copies of MS. 834 in the Barberini Library, which manuscript has now presumably been transferred to the Vatican, at the same time as the other contents of that Library. One of these copies had been made by the Cavaliere Cassiano del Pozzo, who had given it in 1640 to M. Chanteloup, by whom it was presented to du Fresne for the preparation of his edition; the other was lent him for the same object by M. Thevenot. 

Another edition of the Treatise was issued in 1817 by Guglielmo Manzi, who took as his text a manuscript in the Vatican Library (Cod. Vat. [Urbinas], 1270), which had formerly belonged to the Library of the Dukes of Urbino. This manuscript is by far the more complete of the two, Rve out of the eight books which it contains being wanting in the version followed by du Fresne. There are, however, many omissions in Manzi's edition, and the only adequate critical edition of the Vatican manuscript is that published by H. Ludwig (Leonardo da Vinci: Das Buck von der Malerei [Bd. xv-xviii of Quellenschriften fur Kunstgeschichte, etc., Edit. R. Eitelberger v. Edelberg], Vienna, 1882, Stuttgart, 1885). This contains the complete text, together with a German translation and commentary, and also an analysis of the differences which exist between the manuscripts in the Vatican and Leonardo's own manuscripts. 

The Vatican manuscript probably dates from the beginning of the sixteenth century. It has been ascribed to some immediate pupil of Leonardo's, for choice either Francesco Melzi or Salai, but there is no evidence which can be held to establish this view. Its close connection with Leonardo is, however, indisputable. Whether this be the original form or no, the compilation was undoubtedly made previous to the dispersal of the manuscripts. About a quarter of the whole number of paragraphs (two hundred and twenty-five out of nine hundred and forty-four) are identical with passages in the extant manuscripts. Many others, which are not now to be found in any form in the manuscripts, yet carry their lineage incontestably, and would afford a sufficient proof, were this lacking in the chequered history of the various volumes, that some of the manuscripts have now perished: that, as with Leonardo as painter so also as writer, time has spared only the fragments of his work. The compiler of the Treatise on Painting had access to manuscripts, and also probably to sources of information as to the artist's intentions, of which we have no record. He presumably followed what he conceived to be the scheme of the artist's work. Nevertheless, Leonardo cannot be adjudged directly or even indirectly responsible for the arrangement and divisions of this treatise, and it is somewhat difficult to credit him with the whole of the contents. Certain of the passages read rather as repetitions by a pupil of a theme expounded by the master. Did Leonardo himself ever give his work definite shape?

 Did he write a treatise on painting or only parts of one? In Fra Luca Pacioli's dedication to Ludovic Sforza of the De Diuina Proportione , dated February 9th, 1498, he speaks of Leonardo as having finished 'il Librode Pictura et movimenti humani', and Dr. Ludwig, who apparently 
accepts this statement, puts forward the supposition that the treatise was in the possession of Ludovic and probably became lost at the time 
of the French invasion of Milan. 

On this same occasion, according to both Vasari and Lomazzo, there also perished a treatise by Leonardo on the anatomy of the horse v which he had written in the course of his studies for the Sforza statue. 

Vasari, as we have seen, mentions some writings by Leonardo 'which treat of painting and of the methods of drawing and colouring' as being then in the possession of a Milanese painter, who had recently been to see him in Florence to discuss their publication, and had taken them to Rome in order to carry his intention into effect, though with what result Vasari could not say. These writings are stated to be 'in characters written with the left hand, backwards', and therefore they cannot possibly be identical either with the Barberini or the Vatican manuscripts. Seeing that Vasari wrote during Melzi's lifetime, it is reasonable to infer that this manuscript had at an early date become separated from the others and therefore did not form part of the general mass of the manuscripts which passed into Melzi's possession at Leonardo's death, since Vasari states that he kept these as though they were relics. As to whether this manuscript was identical with the work to which Fra Luca Pacioli referred, there is no sufficient evidence on which to form an opinion. Moreover, the Frate's evidence must not be interpreted too literally. The words of the dedication of the De Divina Proportione, 'tutta la sua ennea massa a libre circa 200000 ascende', would naturally also suggest that the statue of Francesco Sforza was actually cast in bronze, but the general weight of evidence, including that of Leonardo's own letters, forbids any such supposition. So, in like manner, it may perhaps have been that in the case of the Treatise on Painting he may have spoken of the rough drafts and fragments 
as though they were the completed work. 

The work itself grew continually in the mind of the author. It was moulded and recast times without number, as his purpose changed and expanded in his progress along each new avenue of study that revealed afresh the kinship of art and nature. It is certain that he never wrote 'finis'. It is at any rate possible that he never halted in investigation for so long a time as would be necessary to arrange and classify what he had written — that he left all this to a more convenient season. 

Genius, we should remember, is not apt to be synthetic. "