Leonardo da Vinci · every age

What was Leonardo da Vinci doing at 41?

Painter, anatomist, engineer. Started the Mona Lisa at 51

1. c. 1493

   Set down the laws of sliding friction in his notebooks

   Two centuries before they were rediscovered.

   Source: en.wikipedia.org

Portrait: Drawing believed to be a self-portrait, Leonardo da Vinci (c. 1510), public domain, via Wikimedia Commons · source