Isaac Newton · every age

What was Isaac Newton doing at 49?

Invented calculus and gravity theory in a plague year at 23

1. c. 1692

   Lunar theory cost him appetite and sleep

   He said his head never ached except when he studied the Moon's motion.

   Source: en.wikipedia.org

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