Page:Popular Science Monthly Volume 9.djvu/703

Rh of the prodigious length of time that it must have taken to excavate the gorge? We should certainly feel startled when on making the necessary calculations we found that the stream had performed this enormous amount of work in something less than a million years.

The absolute settlement of the question must ever be above our powers. For a few centuries only we have the comparative daylight of historical times; thence backward lies the rapidly-gathering twilight of tradition; beyond that, geological periods the duration of which can be only vaguely guessed at, and beyond all these, far back in past eternity, the epoch when Time began. The old belief, which limited the existence of the earth to less than seven thousand years, gave way once for all, almost within living memory. All men are now agreed that the six days of creation were periods of indefinite extent. They are not solar days—for evening happened and morning happened three times over before the sun was created. Not being days measured by the sun, we know not how many thousands of years they may have endured. The reaction was sudden and complete. Geology jumped to the conclusion that the past history of the world was without any limits that human imagination could conceive. But in quite recent years, as we have tried to show, the calm light of science has proved that the practical eternity of matter is not more tenable than the arbitrary limitation by which thought was formerly confined.

Sir William Thomson is not so sweeping in his assertion: but then the nature of the problem before him did not require any such opinion at his hands. His argument aimed at disproving Playfair's assertion that neither the heavenly bodies nor the earth offered any evidence of a beginning, or any advance toward an end. If, therefore, Sir William Thomson was able to show that there was good evidence both of a beginning and an end, he was not concerned to speculate how long past time had existed, or when the end would come. His summing up is this: