— Albert Einstein German-born physicist and founder of the theory of relativity 1879 - 1955
Context: It has often been said, and certainly not without justification, that the man of science is a poor philosopher. Why then should it not be the right thing for the physicist to let the philosopher do the philosophizing? Such might indeed be the right thing to do at a time when the physicist believes he has at his disposal a rigid system of fundamental laws which are so well established that waves of doubt can't reach them; but it cannot be right at a time when the very foundations of physics itself have become problematic as they are now. At a time like the present, when experience forces us to seek a newer and more solid foundation, the physicist cannot simply surrender to the philosopher the critical contemplation of theoretical foundations; for he himself knows best and feels more surely where the shoe pinches. In looking for an new foundation, he must try to make clear in his own mind just how far the concepts which he uses are justified, and are necessities.
"Physics and Reality" in the Journal of the Franklin Institute Vol. 221, Issue 3 (March 1936), Pages 349-382