1478 was the year in which Leonardo da Vinci, aged 26, obtained his first official commission and witnessed the Pazzi Conspiracy against the Medici family. In that year, he probably opened his independent workshop, leaving that of his master Andrea del Verrocchio, and, in its final months, he began to paint two paintings representing the Virgin Mary. One of these paintings is very likely the Benois Madonna at the State Hermitage, St. Petersburg; a work that marks a strong change in Leonardo's style and power of expression and his representation of light and human emotions. This book provides an in-depth analysis of Leonardo's growth as an artist in this year, detailing his training, his culture, his collaboration with Verrocchio, and his engagement in the artistic and cultural life of 1460s and 1470s Florence.