The Riemann–Roch Theorem

Well, a Riemann surface is a certain kind of Hausdorf space. You know what a Hausdorf space is, don’t you? Its also compact, ok. I guess it is also a manifold. Surely you know what a manifold is. Now let me tell you one non-trivial theorem, the Riemann–Roch Theorem

— Gian-Carlo Rota’s recollection of Lefschetz lecturing in the 1940’s, quoted in A Beautiful Mind by Sylvia Nasar.

I am unable to fully understand and appreciate the theorem at this point of time, but it is my goal to learn that.