84. No wonder, then, that these men should be startled at their conclusion, and try somehow to evade it. Such an attempt was actually made, and a gleam of lurid light seemed for a moment to illuminate the thick darkness conjured up by the hypothesis. It was conjectured that the visible universe might in reality be infinite, even if the number of stars be not so, and that such a universe might last from eternity to eternity, and if it might not be supposed that such a system could continuously and without interruption afford a habitation for animated beings, yet it might do so discontinuously and by fits and starts, its available energy being recruited by repeated collisions, extending in a series from eternity to eternity. The life of whole systems, perhaps even of whole galaxies, would thus disappear, to be replaced after myriads of ages by the feeble beginnings of an entirely new order of things. Such a hypothesis no doubt contemplates a ceaseless change, and satisfies so far the requirements of energy. But while the structures built are perishable, the stones out of which they are built—the atoms—are supposed to be eternal. It is this eternity of the atom which vitiates the hypothesis, for we shall show in the sequel that this is a doctrine which can only be held by ignoring the fundamental principles of scientific inquiry. Indeed we can hardly escape from the conclusion that the visible universe must in matter, as well as in transformable energy, come to an end. But the principle of Continuity upon which all such arguments are based still demanding a continuance of the universe, we are forced to believe that there is something beyond that which is visible, or that, to use the words of an old writer (which we have inscribed on our title-page),—‘the things which are seen are temporal, but the things which are not seen are eternal.’ 85. Looking back instead of forward—to the origin of this visible universe, rather than to its end, we are brought even more definitely to a similar conclusion. It is perfectly certain, as we shall afterwards see, that the visible universe must have had a beginning in time; but if it be all that exists, then the first abrupt manifestation of it is as truly a break of continuity as its final overthrow. It may sound strange to some of our readers to be told that it is the duty of the man of science to push back the Great First Cause in time as far as possible; nevertheless, this accurately represents the part in the universe which he is called upon to play.