His work at Milan was important and varied. As a sort of general factotum for the ruler, he was principal engineer in his numerous' military enterprises, constructed the Martesana Canal, and directed great festivities, as when Lodovieo married his niece to the Emperor He was also active as an architect, being one of those employed upon the Cathedral of :Milan, and he probably designed other public buildings. He found time to prosecute his studies in anatomy, especially of animals, with Marco della Torre, and to assist Luca Paeioli in one of his mathe matical works. At the same time he was at the head of a large and important band of pupils, whether or not they then constituted the sup posed Milanese Academy: for them he probably wrote his Trcatise on Pointing ; and it is certain he designed paintings which they carried out. The artistic task in which Leonardo took chief in terest, and indeed the dearest plan of his life, was a colossal bronze monument to Francesco Sforza, the father of Lodovieo. On it he worked constantly till his departure from Milan in 1499, without having brought it to completion. His interest is attested by the numerous studies of horses, in all manner of positions (Ambrosiana, Milan, and Windsor), in sketches for the /noun 111Plit reliefs in wax and clay. The horse, feet high, was complete when the French occupied Milan in 1500, and formed a mark for the Caseon archers. llad Leonardo been permitted to cast it. this monument would probably have been the greatest. equestrian statue of time Renaissance, surpassing Verrocehio's Colleone as far as the lat ter did Donatello's Cattemelata.
During the last years of the fifteenth century Leonardo executed for the Duke his piece of painting, the "Last Supper," a wall (12coration in the refectory in the Monastery of Santa Maria Belle Grazie, Milan. Owing chiefly to his use- of oil colors directly upon the wall, to neglect, and to the vandalism of monks and soldiers, only a ruin of the grand original re mains, But while for purposes of study it is necessary to refer to the many copies by Leo nardo's pupils, the best of which are those by Marco in Saint Petersburg and in the Royal Academy, London (see illustration), and to Raffaello Morghen's excellent print, the original alone gives the true, though faint, idea of the wonderful lighting and inciting color. The painting was in every respect epoch-making, no less in pictorial qualities than in the remarkable composition. Unlike all previous representations, the Apostles are represented upon one side of a table, their faces to the spectator. They are divided into four groups of three, each complete in itself, but subordinated to the principal action emanat ing from the central figure of Christ. He is just pronouncing the words, "One of you shall betray me," and the painting represents the psychologi cal effect of this announcement upon the Apostles.
This effect is shown not only in the face, the in effable sadness of Christ, the wrath of Peter, the villainy of Judas, hut also in the hands, which are treated with a subtle mastery of pantomime, never before attempted or since equaled. Were the heads gone, the bands alone might tell the story. The figures arc twice life size and every thing is subordinated to architectural effect and sculpturesque composition—the effect of perspec tive being gained by open windows with Lombard scenery in the distance.
Most of the other pictures painted by Leonardo during this period have been lost. His portraits of the Duke, his wife and two children on the wall opposite the "Last Supper," have disappeared. The supposed portraits of the Duke and his wife in the Ambrosiana (Milan) are now attributed to pupils, the latter to Ambrogio de Predis. Of the portraits of Lodovico's two mistresses by Leo nardo, Lucrezia C'rivelli perhaps survives in the so-called "Belle F6ronniere" in the Louvre. which, judging from its plastic character, and the absence of sfumato and of the hands, belongs to the early Milanese period. The small "Holy Family" in Saint Petersburg and the large "Resurrection" in the Berlin Museum arc the work of pupils.
In December, 1499, consequent to the troubles following the expulsion of Duke Lodovieo, Leo nardo left Milan for Venice. To a brief sojourn at Mantua we owe two beautiful drawings of Isabella d'Este (Louvre and Uffizi), though lie never painted for her the desired portrait. He remained at Venice till the end of 1500, and in 1501 we find him again in Florence, assiduously devoted to the study of mathematics. Baring re ceived a commission for an altarpiece from the Servile monks, he designed a cartoon which set, all Florence into commotion. Not only was it frequently copied, but motives and entire figures were adopted by other artists, as by Raphael in his "Madonna with the Lamb" (Madrid). Leo nardo did not himself carry out the oil painting, now in the Louvre, of which it was the model. until a later period. In this the Alathmna, seated in the lap of Saint. Catharine. is represented in the act of lifting up the Christ child, who plays with a lamb. Contemporaries were particularly impressed by the position of the Christ child, the beautiful studies for which survive in the Acad emy of Venice and at Windsor. The cartoon of the same subject, in possession of the Boyal Acad emy, though undoubtedly by Leonardo. is not, as is commonly supposed, the original, but a variation of the same theme.
In 1502 Leonardo entered the service of Cesare Borgia as a militamy engineer. rendering impor tant services in different parts of Central Italy.