Newton and the cat flap

The story that Isaac Newton cut a cat-sized opening in a door and then a separate one for kittens has circulated for a long time, but contemporary evidence for it has not been found. The earliest known written version cited by researchers appeared in an 1827 memoir, a century after his death; the memoirist himself expressed doubt about its truth. It is better treated as a later anecdotal legend than as an established episode in Newton’s life. The illustration is AI-generated and does not depict a real room.