Page:Popular Science Monthly Volume 28.djvu/265

Rh say that to the mathematician the language involves a necessary catastrophe, and that if the sun did stand still, even fur a moment, no one would be left to tell the tale.

It is true that all men are not mathematicians, and that it is impossible for a mind which has not studied physical science mathematically fully to estimate the impression of contradiction and impossibility produced upon the mind which has so studied by an allegation of any irregularity in the clock of Nature. Be it observed that the belief in the uniformity of such a phenomenon as the rising of the sun, or of the effect of the moon on the tides, or of such observed facts as precession and nutation, and many others, is to the mathematical physicist something different in kind from that which arises from mere experience. If you say that the sun has risen millions of times already, and therefore will probably, or almost certainly, rise to-morrow, you offer a good presumptive argument; but it is not the argument which chiefly weighs with the man who knows what the rising of the sun means, and what would be the mechanical result of his failing to do so. My belief, however, is, that the feeling of certainty as to natural phenomena, which such men as Laplace felt for the first time in human history, has percolated (so to speak) through the strata of human intelligence until it has become the common property of almost all. The whole aspect of Nature has been changed; and many a man feels a persuasion of the existence of something which may be described as uniformity, and in virtue of which he questions or doubts or denies many things which would have been accepted as possible or probable in the seventeenth century, without knowing or being able to explain upon what his convictions rest.

Hence, according to my view, the uniformity of Nature, instead of being capable of being defended as a postulate, is, so far as it is true, the result of very hard scientific fighting. In the region of celestial mechanics it may be said to have gained absolute sway, because the motions of the heavens resolve themselves into the ordinary laws of mechanics, supplemented by the law of universal gravitation; and from this region there is a very intelligible tendency to extend the assertion of the principle to other departments of scientific investigation. Such extension, however, must be made with caution; even in the solar system itself, the moment we go beyond mechanics, all uniformity appears to vanish. With regard to size, arrangement, density, in fact every element of planetary existence, variety, which defies all kind of classification, not uniformity, is the undoubted order of Nature.

There is a striking paragraph on this subject from the pen of no less a man than Alexander von Humboldt, which it may be well to quote in this connection. After speaking of the absence of all known law connecting the various planetary elements, their magnitudes, densities, etc., he proceeds thus: