We men of science at least need not share their views or their fears. Our feet are set, not on the shifting sands of the opinions and the fancies of the day, but on a solid foundation of verified truth, which by the labors of each succeeding age is made broader and more firm. To us the past is a thing to look back upon, not with regret, not as something which has been lost never to be regained, but with content, as something whose influence is with us still, helping us on our further way. With us, indeed, the past points not to itself, but to the future; the golden age is in front of us, not behind us; that which we do know is a lamp whose brightest beams are shed into the unknown before us, showing us how much there is in front, and lighting up the way to reach it. We are confident in the advance because, as each one of us feels that any step forward which he may make is not ordered by himself and is not the result of his own sole efforts in the present, but is, and that in large measure, the outcome of the labors of others in the past, so each one of us has the sure and certain hope that, as the past has helped him, so his efforts, be they great or be they small, will be a help to those to come. THOMAS HENRY HUXLEY THREE HYPOTHESES RESPECTING THE HISTORY OF NATURE So far as I know, there are only three hypotheses which ever have been entertained, or which well can be entertained, respecting the past history of nature. I will, in the first place, state the hypotheses, and then I will consider what evidence bearing upon them is in our possession, and by what light of criticism that evidence is to be interpreted. Upon the first hypothesis, the assumption is, that phenomena of nature similar to those exhibited by the present world have always existed; in other words, that the universe has existed from all eternity in what may be broadly termed its present condition. The second hypothesis is, that the present state of things has had only a limited duration, and that, at some period in the past, a condition of the world, essentially similar to that which we now know, came into existence, without any precedent condition from which it could have naturally proceeded. The assumption that successive states of nature have arisen, each without any relation of natural causation to an antecedent state, is a mere modification of this second hypothesis. The third hypothesis also assumes that the present state of things has had but a limited duration; but it supposes that this state has been evolved by a natural process from an antecedent state, and that from another, and so on; and, on this hypothesis, the attempt to assign any limit to the series of past changes is, usually, given up.