Emanuel Lasker, 2nd World Chess Champion, was born #onthisday in 1868.
His reign lasted 27 years (!), but chess was not his only notable interest: for instance, he was also a mathematician who developed the Lasker-Noether theorem, fundamental in commutative algebra!
@lichess His _Manual of Chess_ is still, in my opinion, the best chess book ever published. It helped me understand and appreciate the game instead of just teaching the rules and a few openings, like most, if not all, the others.