Guns, Germs, and Steel
What advantage does a triangular lateen sail have compared to a traditional square sail?
Bartholomew Diaz and the Cape of Good Hope
Bartholomew Diaz and the Cape of Good Hope
The ancient square sail permitted sailing only before the wind; the lateen was the earliest fore-and-aft sail. The triangular sail was affixed to a long yard or crossbar, mounted at its middle to the top of the mast and angled to extend aft far above the mast and forward down nearly to the deck.
Encyclopedia Britannica