"Dynamical variables are what count in physics, not coordinate or gauge transformations."

“One day I had the idea of radiation implosion. As in all ideas that have ever popped up in my head, there is no way I can trace the source.”

“Almost all the serious achievements are simple in principle... the ideas must be sufficiently simple.”

“The inner mysteries of quantum mechanics require a willingness to extend one’s mental processes into a strange world of phantom possibilities, endlessly branching into more and more abstruse chains of coupled logical networks, endlessly extending themselves forward and even backwards in time.”

“... was my first lesson in quantum mechanics, and in a very real sense my last, since the rest is mere technique, which can be learnt from books.”