Nearly all the changes in nature with which we are acquainted belong to three classes,--the mechanical, the chemical, and the organic. Astronomical changes are purely mechanical; and hence the ease with which they may be calculated by mathematics. The universal system of death, which reigns over all animals and plants, is the result of organic laws; and it is this which probably gives to man the strongest impression of the transient nature of sublunary things. But just consider the antagonist agencies to this universal destroyer. I refer to the equally universal system of reproduction, and to the law by which permanence of species is secured. The consequence is, that, while every individual animal and plant dies, the species survives. In the whole history of the animals and plants now existing on the globe, only eight or ten certain examples are on record in which a species has become extinct, and those are some large birds, such as the dinornis and dodo, once inhabitants of the Isle of Bourbon and New Zealand. Every one of the human family, every elephant, every ox, every lion, &c., die, but man, as a species, still lives; and so does the elephant, the ox, and the lion; and most obviously this is a law of nature. How easy, then, for the atheist to evade the force of your argument against the world's eternity, drawn from the ravages of death! He has only to suppose the havoc of individuals by death always to have been repaired by the equivalent operation of reproduction, and that these two agencies have been balanced against each other from eternity; and how will you prove this impossible, except by the absurd metaphysical arguments already considered?