Feynman’s derivation of the Schrödinger equation

R. P. Feynman’s ‘‘path integral’’ approach to quantum field theory emerged from his discovery that the Schrödinger equation could be derived from an expression of P. A. M. Dirac’s involving the action. Feynman gave the history of his discovery in his Nobel lecture, but withheld most of the details; when he did publish the discovery, he did not provide the framework. This article provides some historical background and puts both of Feynman’s presentations together.