The flood has no doubt been checked many times. The glacial periods, of which there seem to have been several in different parts of the earth, and in different geological periods, no doubt checked it when it occurred. But the tide as a whole must have steadily risen, because the progression from lower to higher forms has gone steadily forward. The lower forms have come along; Nature has left nothing behind. The radiates, the articulates, the mollusca, are still with us, but in the midst of these the higher and higher forms have been constantly appearing. The great biological tree has got its growth. Many branches and twigs have died and dropped off, and many more will do so, are doing so before our eyes, but I cannot help doubting that any new branches of importance are yet to appear--any new families or orders of birds, or fishes, or reptiles, or mammals. The horse, the stag, the sheep, the dog, the cat, as we know them, are doubtless the end of the series. One arrives at this conclusion upon general principles. Life as a whole must run its course or reach its high-water mark, the same as life in its particular phases. Man has arrived and has universal dominion; all things are put under his feet. The destiny of life upon the globe is henceforth largely in his hands. Not even he can avert the final cosmic catastrophe which physicists foresee, and which, according to Professor Lowell, the beings upon Mars are now struggling to ward off. Man has taken his chances in the clash of forces of the physical universe. No favor has been shown him, or is shown him to-day, and yet he has come to his estate. He has never been coddled; fire, water, frost, gravity, hunger, death, have made and still make no exceptions in his favor. He is on a level with all other animals in this respect. He has his life and well-being on the same terms as do the fowls of the air and the beasts of the fields. Archbishop Whately thought that primitive man could never have raised himself to a higher condition without external aid--some "elementary instruction to enable his faculties to begin their work." He must have had a boost. Well, the boost was forthcoming, but it was not from without, but from within, through this principle of development, this upward striving that was innate from the first in certain forms of life and of which Whately had no conception. It was the conception of his time that creation was like a watch made and wound up by some power external to itself.