What lead me more or less directly to the special theory of relativity was the conviction that the electromotive force acting on a body in motion in a magnetic field was nothing else but an electric field.
Letter to the Michelson Commemorative Meeting of the Cleveland Physics Society (1952), as quoted by R.S.Shankland, Am J Phys 32, 16 (1964), p35, republished in A P French, Special Relativity, ISBN 0177710756