Einstein’s theory is important in that it exemplifies a method which is in many respects new in theoretical physics and which may prove to be a very powerful method for advancing scientific knowledge. There was no idea that the prediction of the bending of light would fix up Mercury’s perihelion and incidentally explain a two-century old astronomical difficulty. That came straight out of a blue sky. MECHANICAL VERSUS MATHEMATICAL MINDS We sometimes hear it said that “Einstein has overthrown Newton’s theory of gravitation.” That is impossible because Newton did not have any theory of gravitation. He merely laid down the law of gravitation. He told how bodies behaved toward their neighbors; he did not tell why. Newton was not content with the idea of action at a distance through empty space and he tried to explain gravitation by the pressure of the ether on material bodies but he was not satisfied with the results and did not publish them. In the 234 years since many men have tried their hands at devising some sort of machinery that will “explain” gravitation. For human beings are like Toddie of “Helen’s Babies” and want to have the watch opened so they can “see the wheels go wound.” At least Anglo-Saxons have that desire. Poincaré, the French physicist, said this is the distinction between the Anglo-Saxon and Latin minds; the former are uneasy until they can imagine a mechanical model to represent natural phenomena, the latter are satisfied with a mathematical formula expressing the action. The ether, which was invented to explain light, also required “explanation.” Lord Kelvin imagined it to consist of spinning tops which have a sort of mobile stability. Sir Oliver Lodge has filled it with a complicated structure of interlocking geared wheels to account for electro-magnetic action. These are typical Anglo-Saxon modes of thinking. On the other hand, Einstein, who, in spite of his Hebrew blood and German training, has preëminently what Poincaré claims as the Latin temperament, does not have any use for the ether and does not care at all whether he can “picture” the fourth dimensions on paper or not.