The goal of the new theory is not so new at all — it has been pursued with great tenacity by a number of mathematicians and physicists for about ten years now. The great achievement of the theory of relativity was the combining of a series of physical facts under a single law of great scope, yet it had to interrupt its progress upon encountering one last barrier; it could not unite the theory of electricity with the theory of mechanics. Thus two vast bodies of laws stood at the pinnacle of physics. On the one hand, there was the complex of mechanical laws, which happily brought about a union between the phenomena of gravitation and the facts of space-time theory, culminating in Einstein's gravitational field equations; on the other, there was the complex of electrical laws, which had already been formulated in essentials by the Englishman Maxwell by the end of the last century. These two sets of laws had, as it were, nothing to do with each other; the world of physics was divided into two kingdoms, one ruled by Einstein, and the other by Maxwell. The temptation to attempt a supreme union was irresistible: however, nature proved to be more stubborn than had been anticipated.