Perhaps people mistook Dan Brown as authoritative on the matter. I browsed the read samples of some of the top listed books on Leonardo da Vinci on Amazon, and all use "Leonardo" in their introduction whenever they do not refer to him as "Leonardo da Vinci". I found no single isolated "da Vinci". See:

https://www.amazon.com/-/en/dp/0715324535

https://www.amazon.com/-/en/dp/B0DHFRBMF3

https://www.amazon.com/-/en/dp/1501139169

The standard way to avoid confusion is to introduce him as "Leonardo da Vinci" and later just say "Leonardo".

Ah, that makes sense. Your answers are really well researched, it raises the standard of the forum. Thanks!

Yes, because we interpret "da Vinci" as a surname, which it isn't, at least not exactly.

But in fact, the man your college friend-group calls "Johnny from the Bronx" in English would not be shortened to "from the Bronx".

> Leonardo could be anyone for all I know

If the topic is sketching and someone refers to Leonardo, you should know who it is.

It's like referring to "Michael" when talking about basketball.

I definitely thought of the aerospace/defense company before the polymath.

Actually, the company was (re)named after Leonardo da Vinci, see: https://www.defensenews.com/industry/2016/04/28/it-s-officia... (and then not named "Da Vinci").

> Leonardo could be anyone for all I know

Indeed. There was a famous Leonardo from Pisa. Son of Bonacci.