Partial Differential Quotes (2 quotes)
I did some very technical work in partial differential equations, made an unsuccessful pass at shock waves, worked in scale invariant variational problems, made a poor stab at three manifold topology, learned gauge field theory and then some about applications to four manifolds, and have recently been working in equations with algebraic infinite symmetries. I find that I am bored with anything I understand. My excuse is that I am too poor an expositor to want to spend time on formal matters.
Laplace’s equation is the most famous and most universal of all partial differential equations. No other single equation has so many deep and diverse mathematical relationships and physical applications.