Aby Warburg delivered his Lectures on Leonardo in 1899 to introduce himself as a young art historian and private scholar to the wider public. These texts are now published for the first time, fully illustrated and translated into English. The lectures give an insight into Warburg as a public speaker, concerned to convey a complex visual argument to a non-specialist audience, and discuss Leonardo's artistic development in three steps: his training and early years in Florence, work at the Sforza court in Milan, and final years in Florence and France.