tion; the latter must follow the former, and constitute its completion. The change from the one to the other is always attended with prodigious impulse to science.
To illustrate: Until Kepler, astronomy was little more than an accumulation of disconnected facts concerning celestial motions—abundant materials, but no science; piles of brick and stone, but no building. Kepler reduced this chaos to beautiful order and musical harmony by the discovery of the three great laws which bear his name, and therefore he has been justly called the legislator of the heavens—the lawgiver of space. But, had he been asked the cause of these beautiful laws, he could only have answered, "The first cause—the direct will of the Deity." A good answer and a true, but not scientific; because it places the question beyond the domain of science, which deals only with second or physical causes. But Newton comes forward and gives a physical cause. He shows that all these beautiful laws are the necessary result of gravitation; and thus astronomy becomes a physical science. So, until Agassiz, the facts of geological succession of organic forms were in a state of lawless confusion. Agassiz by establishing the three great laws of succession, which ought to bear his name, reduced this chaos to order and beauty; and, therefore, he might justly be called the legislator of geological history—the law-giver of time. But, when asked the cause of these laws, he could only answer, and did indeed answer, "The plans of the Creator." A noble answer and true, but not scientific. Darwin now comes forward and gives, partly at least, the cause of these laws. He shows that all these beautiful laws are explained by the doctrine of "origin of species by derivation with modifications"; that these laws are not ultimate, but derivative from more fundamental laws of life; and thus biology is advanced one step, at least, toward the causal stage. Newton and Darwin substituted second causes for first cause—natural for supernatural. They each in his own department broke the bonds of supernaturalism in the domain of Nature.
One more important reflection: There are two, and only two, fundamental conditions of material existence—space and time. There are, therefore, two, and only two, cosmoses—space-cosmos and time cosmos. These have been redeemed from confusion and reduced to law and order and beauty—changed from chaos to cosmos—by science. For this result we are chiefly indebted, in the one case, to Kepler and Newton; in the other, to Agassiz and Darwin. The universal law, in the one cosmos, is the law of gravitation; in the other, the law of evolution. Traced by analysis to its deepest roots of philosophic truth, the one law may be called the divine mode of sustentation; the other, the divine process of creation.
Or, again: we have all heard of the "music of the spheres"—a beautiful and significant name used by the old thinkers for the divine order of the universe—a music heard not by human ear, but only