Elephant souls

...the dissection of an elephant, which led Locke to joke that if this revealed that this huge animal's pineal gland was proportionably large, the Cartesians would have to say it had a large soul: "but if it is true that elephants can write I wouldn't want them to be given paper and ink lest they leave to posterity in their memoirs that we are nothing but machines and that only they have understanding".

Locke is often thought of as rather bloodless and austere, and the biography by Roger Woolhouse doesn't do a lot to dispel that image, but there are occasional flashes of wit.