Cat doors may have been invented by Sir Isaac Newton.
Many know Isaac Newton as the renowned physicist, astronomer, and mathematician. In addition to Newton's several laws of motion and the “apple incident” for which he is best known, Newton may also have invented the cat flap, or cat door.
In a story by a “County Parson,” the invention of the cat flap is attributed to Newton. It goes on to say that Newton foolishly made a large hole for the mother cat and a small one for her kittens, not realizing the kittens would follow the mother through the large one. The accuracy of the story is debated, because though biographies of Newton had said he kept “neither cat nor dog in his chamber,” it had been verified that there were two plugged holes in his door with the right size for a cat and kitten.