Many civilizations have independently discovered ways to optimize for the wind power. They all learned to sail in all directions, regardless of which way the wind is blowing. There are really only two tricks: the shape of the sail and the keel under the water.
Sails are not a flat surface, it is curved. When the wind is behind the boat, the curved surface captures the wind like a bag and the boat get pushed forward. When the wind blows from the side, the wind on the convex side must travel faster than the concave side. The difference in wind speeds creates a pressure differential: the Bernoulli effect. It is like the wind is pushing and pulling the boat at the same time.
The keel counters the side-way force (leeway) under the water. It works exactly the same, just with water instead of the wind. When the wind pushes the boat to the side, the water, through the keel, pushes back. The result is the boat moving straight. Magic of Physics!
Before I took lessons, I thought “running” (sailing downwind) is what sailing is all about. In fact, the fastest direction is when the wind is blowing from the side (beam reach). At that moment, it feels like the boat is flying. The most enjoyable direction is probably when the wind is blowing against you from an angle (close reach). You feel the wind blowing across your face and there is very little work to get the boat moving.
I can see this craft takes a life-time to master and also why it is addictive.