Significance of His Discovery.—The philosophic importance of the discovery that the motions of the planets may be explained by the "law of gravitation" was twofold. In the first place, it now became possible to understand how the universe held together (a problem which the new astronomy had not solved); and in the second place, the theory constituted a large extension of the mechanical view. It demonstrated that "the physical laws which hold good on the surface of the earth are valid throughout the universe, so far as we can know anything of it." Thus the area of existence in which physical law held good was at once infinitely widened. The mechanical theories of Galileo, Descartes, and others, not only received confirmation, but became more comprehensive than before.
So that Newton may be said to have put the finishing touch upon the achievements of his predecessors, and to have crowned their labours with success. And his work has the characteristic of permanency: his "gravitation formula" has stood the test of time. "It still stands there," says a careful and authoritative writer, "as almost the only firmly established mathematical relation, expressive of a property of all matter, to which the progress of more than two centuries has added nothing, and from which it has taken nothing away."[6]
Religious Corollaries.—It would be a profound mistake to assume that the creators of the mechanical view, as it has hitherto met us, were animated by any hostility to religion. Nor did they believe their theories to involve any disastrous consequences in that sphere.
The new astronomy of Copernicus had actually been made the basis of a spiritual view of the universe by the profound genius (both philosophical and religious) of Giordano Bruno. And the fact that the ecclesiastical authorities rejected his view need not divest it of importance or of value in our eyes. Bruno's own faith was not disturbed by the infidelity of his persecutors. "Ye who pass judgment upon me feel, maybe, greater fear than I upon whom it is passed," were his last words to them. Had they believed, they need not have been afraid, and might have been content with the policy of Gamaliel.
As for Descartes and Hobbes, their notions were no doubt distasteful to conservative minds (the Jesuits were no friends to either), but Descartes regarded himself, and would fain have been regarded by others, as a good Catholic; and Hobbes, theologically, was what in these days we might call a Liberal Protestant. Cartesianism, as we have seen, came to be a name for a type of thought which studied to harmonise science and theology, and one of the most profound religious geniuses of any age—Pascal, was (as we have seen) a Cartesian.
As for Newton, his view of the universe was essentially a religious one, though he did not allow theological speculations to intrude upon his strictly scientific work. His attitude is indicated by a reply to the inquiry of a contemporary theologian as to how the movements and structure of the solar system were to be accounted for.
"To your query I answer that the motions which the planets now have could not spring from any natural cause alone.... To compare and adjust all these things together (i.e. quantities of matter and gravitating powers, etc.) in so great a variety of bodies, argues the cause to be not blind and fortuitous, but very well skilled in mechanism and geometry."[7]
Still, the mechanical view contained within it sinister possibilities; and the instincts of conservative thinkers were not altogether at fault. The mechanical view in itself need not be hostile to a spiritual and rational religion (though it is fatal to most forms of superstition); and yet that view can be used in the interests of anti-religious prejudice—and, as we shall see, it was so used, and with considerable effect.
Meanwhile, however, we shall pass on to consider the work of three thinkers who are typical of a revolt from what was in danger of becoming the all-absorbing tyranny of mechanics. This reaction (for so it may be termed) we shall proceed, in the following chapter, to examine.