“If, for the sake of giving definiteness to our notions, we were to assume that the numbers which express the antiquity of these four periods—the present organic condition of the earth; the tertiary period of geologists which preceded that; the secondary period which was anterior to that; and the primary period which preceded the secondary—were _on the same scale_ as the numbers which express these four magnitudes:—The magnitude of the earth; that of the solar system compared with the earth; the distance of the nearest fixed stars compared with the solar system; and the distance of the most remote nebulæ compared with the nearest fixed stars,—there is, in the evidence which geological science offers, nothing to contradict such an assumption. And as the infinite extent which we necessarily ascribe to space allows us to find room, without any mental difficulty, for the vast distances which astronomy reveals, and even leaves us rather embarrassed with the infinite extent which lies beyond our furthest explorations; so the infinite duration which we, in like manner, necessarily ascribe to past time, makes it easy for us, so far as our powers of intellect are concerned, to go millions of millions of years backwards, in order to trace the beginning of the earth’s existence—the first step of terrestrial creation.” To return, however, to the course of the argument. We hear the oppressed observer asking, as he reascends this “long staircase of natural steps” which had brought time down to the mystic origin of animal existence; his eye dimmed with its efforts to “decipher,” in the picturesque language of Sir David Brewster, “downwards, the pale and perishing alphabet[23] of the Chronology of Life”—WHERE, ALL THIS WHILE, WAS MAN? Were Europe at this moment to be submerged beneath the ocean, or placed under a vast rocky stratum, what countless proofs would present themselves to the exploring eyes of remote future geologists, of the existence of both Man and his handiwork!—of his own skeleton, of the products of his ingenuity and power, and the various implements and instruments with which he had effected them! The rudest conceivable work of human art would carry us to any extent backward, but it is not to be found! Man’s existence and history incontestably belong to the existing condition of the earth; and the Essayist now addresses himself to the two following propositions:— _First_, That the existence and history of man are facts of an Entirely Different Order from any which existed in any of the previous states of the earth. _Secondly_, That his history has occupied a series of years which, compared with geological periods, may be regarded as very brief and limited. Here opens the “Argument from Geology”—and with it Chapter VI.