Abstract
The project to divert the flow of the Arno occupied Leonardo da Vinci’s mind during the troubled years of 1503-1504, as he was commissioned by the city of Florence to investigate its feasibility, and to study its military consequences in the war against Pisa. Aside from the “Leonardian” aspects of the project (such as the dream of mastering the power of nature, or the fascination for spirals and waves, etc.), this article sets out to cast some light on its historical and political context. Indeed, the reading of the verbali gathered together in the Consulte e Pratiche della Republica fiorentina authorizes us to see Leonardo from a different perspective, and to ask some interesting questions: how does the idea of diverting the river echo the imagination of the men of his time ? What were the real aims of the city in hiring Leonardo: to use his genius, or only his name and reputation as Borgia’s military engineer? And how, finally, does the Leonardian project match Piero Soderini’s political vision of Florence’s country planning ?