… for it is very probable, that the motion of gravity worketh weakly, both far from the earth, and also within the earth: the former because the appetite of union of dense bodies with the earth, in respect of the distance, is more dull: the latter, because the body hath in part attained its nature when it is some depth in the earth.

{Foreshadowing Isaac Newton's Universal Law of Gravitation (1687)}

A number of years ago, when I was a freshly-appointed instructor, I met, for the first time, a certain eminent historian of science. At the time I could only regard him with tolerant condescension.

I was sorry of the man who, it seemed to me, was forced to hover about the edges of science. He was compelled to shiver endlessly in the outskirts, getting only feeble warmth from the distant sun of science- in-progress; while I, just beginning my research, was bathed in the heady liquid heat up at the very center of the glow.

In a lifetime of being wrong at many a point, I was never more wrong. It was I, not he, who was wandering in the periphery. It was he, not I, who lived in the blaze.

I had fallen victim to the fallacy of the 'growing edge;' the belief that only the very frontier of scientific advance counted; that everything that had been left behind by that advance was faded and dead.

But is that true? Because a tree in spring buds and comes greenly into leaf, are those leaves therefore the tree? If the newborn twigs and their leaves were all that existed, they would form a vague halo of green suspended in mid-air, but surely that is not the tree. The leaves, by themselves, are no more than trivial fluttering decoration. It is the trunk and limbs that give the tree its grandeur and the leaves themselves their meaning.

There is not a discovery in science, however revolutionary, however sparkling with insight, that does not arise out of what went before. 'If I have seen further than other men,' said Isaac Newton, 'it is because I have stood on the shoulders of giants.

Human nature with all its infirmities and deprivation is still capable of great things. It is capable of attaining to degrees of wisdom and goodness, which we have reason to believe, appear as respectable in the estimation of superior intelligences. Education makes a greater difference between man and man, than nature has made between man and brute. The virtues and powers to which men may be trained, by early education and constant discipline, are truly sublime and astonishing. Isaac Newton and John Locke are examples of the deep sagacity which may be acquired by long habits of thinking and study.

Newton supposed that the case of the planet was similar to that of [a ball spun around on the end of an elastic string]; that it was always pulled in the direction of the sun, and that this attraction or pulling of the sun produced the revolution of the planet, in the same way that the traction or pulling of the elastic string produces the revolution of the ball. What there is between the sun and the planet that makes each of them pull the other, Newton did not know; nobody knows to this day; and all we are now able to assert positively is that the known motion of the planet is precisely what would be produced if it were fastened to the sun by an elastic string, having a certain law of elasticity. Now observe the nature of this discovery, the greatest in its consequences that has ever yet been made in physical science:—

I. It begins with an hypothesis, by supposing that there is an analogy between the motion of a planet and the motion of a ball at the end of a string.

II. Science becomes independent of the hypothesis, for we merely use it to investigate the properties of the motion, and do not trouble ourselves further about the cause of it.

[All phenomena] are equally susceptible of being calculated, and all that is necessary, to reduce the whole of nature to laws similar to those which Newton discovered with the aid of the calculus, is to have a sufficient number of observations and a mathematics that is complex enough.