Q. In CMOS 16.71, why is Leonardo da Vinci indexed under “L”? And in an article that refers to people by surnames on subsequent mention, should he be referred to as “Leonardo” or “da Vinci”?
A. You can ignore Dan Brown and others who’ve rebranded the archetypal Renaissance man as “Da Vinci.” The name is Leonardo, and he came from Vinci (da Vinci), an Italian town in the region of Tuscany.
Leonardo can be referred to in full as Leonardo di ser Piero da Vinci (as noted on page 69 of Walter Isaacson’s 2017 biography, Leonardo da Vinci [Simon & Schuster])—in which “di ser Piero” means he’s the son of a man named Piero (ser is an old social title that was similar to “sir”). Leonardo’s father was also da Vinci, which isn’t a surname but rather an epithet (see CMOS 8.34). Leonardo and Piero are given names (i.e., first names).
Because he lacks a surname, Leonardo da Vinci is properly indexed under “L” and would be referred to in the text as Leonardo—that is, after having been introduced as Leonardo da Vinci.