law of inertia according to a ratio which corresponds to the law of falling bodies at the earth's surface. He then deduces the mathematical consequences of this idea and finally shows that the results of this deduction agree with the facts as actually observed. From this he concludes that the motion of the heavenly bodies is governed by the same law as falling bodies. He calls the energy which manifests itself in this law attraction (attractio). He does not introduce any mystical energy. By attraction he means only an energy which acts according to the well-known law of falling bodies—which likewise constitutes the energy.—As a matter of fact he was later inclined, and his disciples even more so, to regard attraction as an original energy proceeding directly from God.
The expositions of Newton’s masterpiece likewise involve presuppositions and speculative ideas which are of philosophical importance. He makes a distinction between "absolute, true, and mathematical space" and sensible spaces. Absolute motion occurs in the former alone, because it contains absolute places (loca primaria), places which are at once places for themselves (sine relatione ad externum quodvis) as well as for other things. Following Copernicus and Kepler , Newton defends the ancient theory of absolute space. He does not simply regard the mathematical method of interpretation as a way of looking at things, which may be regarded as mathematically fundamental, but rather as the true method of interpretation in contrast with the popular or common-sense method. And he even connects this with religious ideas: Space is the sensorium dei, the instrument of the divine omnipresence.
Newton proves the existence of God from the purposeful and harmonious arrangement of the universe, which is
