Leonardo was born in Vinci on 15 April 1452, the illegitimate son of the notary Ser Piero d’Antonio and of a woman named Caterina. His grandfather Antonio made a note of his birth on the last page of a notarial protocol of his father, Ser Piero di Ser Guido, a protocol already used to record the births of his sons: “1452. On Saturday the 15th April, at 3 am, my grandchild was born, the son of my son, Ser Piero. He was called Lionardo. He was baptised by the priest Piero di Bartolomeo from Vinci”.