Isabella d'Este, the marchioness of Mantua, was a collector of antiquities, a patron of art, and one of the most vivid personalities of the Italian Renaissance. Her artistic relationship with Leonardo da Vinci (1452-1519) is charted through the letters that they exchanged over the course of about six years. Beginning in late 1499, Leonardo spent several months in Mantua, where he met Isabella and produced a finished portrait drawing of her. In the years that followed, the marchioness wrote to the artist to ask him to undertake other paintings and projects. Though little came of these requests, da Vinci did produce a drawing of some classical hard-stone vases to assist her search for collectible antiques and also started work on a painting of Christ as a twelve-year-old boy at her request. The story of their relationship is explored in depth for the first time in Isabella and Leonardo. This illuminating story raises interesting and important questions about relationships between artists and patrons, and about women as art patrons at the beginning of the 16th century.