I am lecturing at the Nesin Mathematics Village. There are no lectures today; a colleague organised a tour of Miletus, ruins of an ancient city where Thales, perhaps the first mathematician known to us by name, was born and lived. I am reading a fascinating old book Aegean Turkey by George E. Bean. His style is charming:
Thales also, we read, was the first man to succeed in inscribing a right-angled triangle in a circle; in celebration of this he sacrificed an ox — which means in effect that he stood himself a good dinner.
Mathematicians should definitely keep alive the tradition of celebrating a new theorem with a good dinner.
By the way, Bean makes the following remark regarding the result that, in Thales opinion, deserved a dinner of an ox:
There is something wrong here. The least mathematically-minded can inscribe a right-angled triangel in a circle. Unless we should read `equilateral triangle’, the meaning is probably that Thales first proved that a triangle inscribed in a semicircle is right-angled.