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Sir Isaac Newton and the Cat Door

Sir Isaac Newton and the Cat Door

Sir Isaac Newton is credited with inventing the cat door. The story goes that Newton wanted his cats to have access to every room. Newton cut a hole and hung a black cloth over the openings to keep the light out, so that his cat could pass through, thereby inventing the first cat door.

However there is evidence that cat flaps (or at least cat holes) existed centuries before Isaac Newton was born.

Cat door and isaac newton

Is It A Myth?

It may well be a myth, the story of Newton inventing the cat flap first came to light back in 1893 when a series of anonymous anecdotes about Newton were published.

Because they are anonymous it is impossible to verify their truth.

Two historians and biographers both attest that there is no evidence that Newton kept either dogs or cats.

The cat flap is also such a simple invention that many historians suspect it was invented far earlier than 1700.

isaac newton and the cat door fact or myth

In fact, Geoffrey Chaucer described a primitive cat flap in “The Miller’s Tale” from his Canterbury Tales collection which was published in the late 14th century.

In his tale a servant looks through a door using the cat flap:

“An hole he foond, ful lowe upon a bord
Ther as the cat was wont in for to crepe,
And at the hole he looked in ful depe,
And at the last he hadde of hym a sighte.”

So it seems the invention of the cat flap (or at least cat hole) significantly predates Newton.

Truth To The Myth

One piece of evidence which suggests that this myth may be true is a quote from one of Isaac Newton’s alma mater Trinity College colleagues, J. M. F. Wright, who said “Whether this account be true or false, indisputably true is it that there are in the door to this day two plugged holes of the proper dimensions for the respective egresses of cat and kitten.”

Newton is said to have made an additional hole for the cat’s kitten, seemingly unaware that they would easily be able to get through the same hole as their mother.


While it’s not known for certain who invented the cat flap it sees that cat flaps had been around for centuries before 1700 when Sir Isaac Newton is said to have invented them.

The reality is that cat flaps were probably more of an informal invention which were used infrequently by cat owners.

It is unlikely that Sir Isaac Newton invented them but because he was the first well-known person to use them their invention was attributed to him.



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