After a dozen years at the court of Lodovico Sforza, the Duke of Milan, Leonardo da Vinci was at a low point personally and professionally. Despite a number of prestigious commissions, he had reached the age of 43 – more than the average life expectancy for the day – without having completed a major work that fulfilled his astonishing promise, when at last the challenge arose. In this richly illustrated talk, Ross King shows how Leonardo created a masterpiece that would forever define his reputation.