In the second place, still deeper will be this impression, when we recollect that similar transmutations have already been experienced by the earth with an improvement of its condition. There is no evidence that the entire surface of the earth has ever undergone a complete fusion since organic life first appeared upon it. But we have reason to think that, frequently, at least, when one race of animals and plants has disappeared from the earth, it has been the result of violent catastrophes, proceeding from the elevation or subsidence of continents or chains of mountains. Says Agassiz, "A very remarkable, and perhaps the most surprising fact is, that the appearance of the chains of mountains, and the inequalities of the surface resulting from it, seem to have coincided generally with the epochs of the renewal of organized beings."--_Ed. Journal of Science_, Oct. 1842, p. 394.--These vertical movements of such large portions of the earth's crust could have resulted only from the direct or indirect agency of volcanic power, though the destruction of organic life, which must have been the consequence, may have resulted as often from aqueous as igneous inundations. But usually both agencies were probably concerned, and the predominance of one or the other of these agencies is of little consequence to the argument; for if such wide-spread ruin has already repeatedly passed over the earth, a still wider desolation may be presumed possible, if only a little wider play shall be given to the agents of destruction. Already have the changes of this sort which the earth, or portions of it, have undergone, resulted in an improved condition of its surface. In other words, at each successive epoch, animals and plants of a higher and more perfect organization have appeared, because the temperature, the air, and the earth's general condition have been better adapted to their happy existence. The amount of limestone seems to have been constantly increasing, and, as a consequence, the fertility of the soil; probably, also, the amount of carbonic acid has diminished in the atmosphere, as animals with lungs have been multiplied. In short, there is a prodigious increase, among the present inhabitants of the globe, of animals and plants possessing complicated and delicate organization and loftier intellectual powers, over all former conditions of the globe. But we have reason to believe, from the Christian Scriptures, that the next economy of life which shall be placed upon the globe will far transcend all those that have gone before. Every vestige of sin, suffering, decay, and death will disappear. Says the Bible, _There shall be no more death, neither sorrow nor crying, neither shall there be any more pain, for the former things are passed away. And there shall in no wise enter it any thing that defileth, neither whatsoever worketh abomination, or maketh a lie._ In short, the change is no other than the conversion of this world into heaven.