[RightWingAtheist]

I thought that differential geometry had been developed years before by Gauss, Lobachevsky and Bolyai, and that it was Minkowski (ironically enough, Einstein's old teacher, and the one who infamously called him "lazy", resulting in one of the most persistent falsehoods surrounding the great man that he had been a poor student) who demonstrated its usefulness in explaining general relativity.

[Southack]

Leonhard Euler (1707-1783)
was extremely prolific in a vast range of subjects, and founded mathematical analysis. He invented the idea of functions and used them to transform analytic into differential geometry investigating surfaces, curvature, and geodesics. He discovered (1752) that the well-known "Euler characteristic" (V-E+F) of a polyhedron depends only on the surface topology. Euler, Monge, and Gauss are considered the three fathers of differential geometry. He also made breakthroughs contributions to many other branches of math. A representative selection of his discoveries is given in Euler: The Master of Us All.

[Doctor Stochastic]

Levi-Cita

[Excuse_My_Bellicosity]

I happen to be reading a book on the subject right now, Faster Than The Speed of Light by Joao Magueijo. I just read his chapter on how Albert Einstein developed General Relativity Theory. He states: "It [General Relativity] is a phenomenally complex theory, requiring the use of a totally new piece of mathematics never seriously used before in physics, Differential Geometry."

Damn my memory. When I read that the first time around, I thought it was essentially saying that Einstein was the father of Differential Geometry. Not so, he was just the first person to apply it to physics.