<P> These notebooks--originally loose papers of different types and sizes, distributed by friends after his death--have found their way into major collections such as the Royal Library at Windsor Castle, the Louvre, the Biblioteca Nacional de España, the Victoria and Albert Museum, the Biblioteca Ambrosiana in Milan, which holds the twelve - volume Codex Atlanticus, and British Library in London, which has put a selection from the Codex Arundel (BL Arundel MS 263) online . The Codex Leicester is the only major scientific work of Leonardo in private hands; it is owned by Bill Gates and is displayed once a year in different cities around the world . </P> <P> Leonardo's notes appear to have been intended for publication because many of the sheets have a form and order that would facilitate this . In many cases a single topic, for example, the heart or the human fetus, is covered in detail in both words and pictures on a single sheet . Why they were not published during Leonardo's lifetime is unknown . </P> <P> Leonardo's approach to science was observational: he tried to understand a phenomenon by describing and depicting it in utmost detail and did not emphasise experiments or theoretical explanation . Since he lacked formal education in Latin and mathematics, contemporary scholars mostly ignored Leonardo the scientist, although he did teach himself Latin . In the 1490s he studied mathematics under Luca Pacioli and prepared a series of drawings of regular solids in a skeletal form to be engraved as plates for Pacioli's book De divina proportione, published in 1509 . </P> <P> The content of his journals suggest that he was planning a series of treatises to be published on a variety of subjects . A coherent treatise on anatomy was said to have been observed during a visit by Cardinal Louis' D' Aragon's secretary in 1517 . Aspects of his work on the studies of anatomy, light and the landscape were assembled for publication by his pupil Francesco Melzi and eventually published as Treatise on Painting by Leonardo da Vinci in France and Italy in 1651 and Germany in 1724, with engravings based upon drawings by the Classical painter Nicolas Poussin . According to Arasse, the treatise, which in France went into 62 editions in fifty years, caused Leonardo to be seen as "the precursor of French academic thought on art". </P>

When did leonardo da vinci start creating art