In fact, I have attained a point at which it will be advisable to strengthen my position by reversing my processes. So far, we have gone on _à priori_, from an abstract consideration of _Simplicity_, as that quality most likely to have characterized the original action of God. Let us now see whether the established facts of the Newtonian Gravitation may not afford us, _à posteriori_, some legitimate inductions. What does the Newtonian law declare?—That all bodies attract each other with forces proportional to their quantities of matter and inversely proportional to the squares of their distances. Purposely, I have here given, in the first place, the vulgar version of the law; and I confess that in this, as in most other vulgar versions of great truths, we find little of a suggestive character. Let us now adopt a more philosophical phraseology:—_Every atom, of every body, attracts every other atom, both of its own and of every other body, with a force which varies inversely as the squares of the distances between the attracting and attracted atom._—Here, indeed, a flood of suggestion bursts upon the mind. But let us see distinctly what it was that Newton _proved_—according to the grossly irrational definitions of _proof_ prescribed by the metaphysical schools. He was forced to content himself with showing how thoroughly the motions of an imaginary Universe, composed of attracting and attracted atoms obedient to the law he announced, coincide with those of the actually existing Universe so far as it comes under our observation. This was the amount of his _demonstration_—that is to say, this was the amount of it, according to the conventional cant of the “philosophies.” His successes added proof multiplied by proof—such proof as a sound intellect admits—but the _demonstration_ of the law itself, persist the metaphysicians, had not been strengthened in any degree. “_Ocular_, _physical_ proof,” however, of attraction, here upon Earth, in accordance with the Newtonian theory, was, at length, much to the satisfaction of some intellectual grovellers, afforded. This proof arose collaterally and incidentally (as nearly all important truths have arisen) out of an attempt to ascertain the mean density of the Earth. In the famous Maskelyne, Cavendish and Bailly experiments for this purpose, the attraction of the mass of a mountain was seen, felt, measured, and found to be mathematically consistent with the immortal theory of the British astronomer.