Isaac Newton · every age

What was Isaac Newton doing at 41?

Invented calculus and gravity theory in a plague year at 23

1. Dec 1684

   His tract De motu was copied into the Royal Society register

   Halley's visit to Cambridge had prompted the nine-sheet paper that grew into the Principia.

   Source: en.wikipedia.org

Portrait: Portrait: Godfrey Kneller (1689), public domain, via Wikimedia Commons · source