LEONARDO DA VINCI We now have to pass from the mediocre artists who worked in the school of Domenico Ghirlandaio to that great master, Leonardo da Vinci (1452-1519), whose work in the oil medium can nowhere be studied so profitably as in the Louvre. This many-sided genius was the natural and first-born son of a country notary, and became a pupil of the sculptor-painter, Andrea del Verrocchio, in whose workshop he met Botticelli, Lorenzo di Credi, and many less distinguished Florentine painters. His interests and occupations were so various that a detailed study of his life-work reveals him as scientist, philosopher, architect, sculptor, military engineer, mathematician, botanist, and musician. The _Annunciation_ (catalogued as No. 1602A and labelled No. 1265), which in the official Catalogue is now only attributed to him after having long passed under the name of Lorenzo di Credi, is doubtless an early work of about 1472 by Leonardo. Some ten years later Leonardo entered the service of Lodovico Sforza, Duke of Milan, in which city he shortly afterwards painted the _Virgin of the Rocks_ (No. 1599). This fine painting—whose virtues are concealed under a thick coat of chilled varnish—is reputed to have been in the collection of François I., although it has no continuous pedigree earlier than the year 1625, when it was in the royal collection at Fontainebleau. It is very similar to the painting of the same subject which the National Gallery (No. 1093) purchased in 1880 for £9000. The points of difference between the two versions are numerous but trifling. The nimbi in the National Gallery picture were added much later and are not found in the Louvre panel, which in the greater perfection of detail, in the treatment of the foreground and the brushwork, prove it to be an earlier and more authentic work. A careful examination of the documents which came to light in the year 1893 shows that a dispute arose as to the price to be paid by the Brotherhood of the Conception of Milan for the picture now in the Louvre, and that Ambrogio da Predis and Leonardo da Vinci petitioned the Duke of Milan to intervene. It would seem that the National Gallery picture was executed in great part by Ambrogio, who worked under the supervision of the great Florentine master, in 1494, about twelve years later than the version in this collection. Leonardo’s greatest contribution to Florentine art consisted in his practice of the science of _chiaroscuro_, the laws of which he was the first to fully investigate.