Who can say that after lapse of time changes did not occur, always in obedience to conditions stamped upon him at the Creation? A simpler illustration carries us to the same result. A cog-wheel, so common in machinery, operates ordinarily by the cogs on its rim; but the wheel may be so constructed, that, after a certain series of rotations, another set of cogs is presented, inducing a different motion. All can see how, in conformity with preëxisting law, a change may occur in the operations of the machine. But it was not less easy for the Creator to fix His law at the beginning, according to which the evolutions of this world proceed. And thus are we brought back to the conclusion, so often announced, that unity of origin must not be set aside simply because existing varieties of Man cannot be sufficiently explained by known laws, operating during that brief period which we call History. In considering this great question, there are authorities which cannot be disregarded. Count them or weigh them, it is the same. I adduce a few only, beginning with Latham, the ethnologist, who insists,-- “(1.) That, as a matter of fact, the languages of the earth’s surface are referable to one common origin; (2.) that, as a matter of logic, this common origin of language is _primâ facie_ evidence of a common origin for those who speak it.”[137] The great French geographer and circumnavigator, Dumont d’Urville, testifies thus:-- “I see on the whole surface of the globe only three types or divisions of mankind which seem to me to merit the title of distinct races: the white, more or less colored with red; the yellow, inclining to different tints of copper or bronze; and the black.--I share in the opinion which refers these three races to one and the same primitive stock, and which places their common cradle on the central plateau of Asia.”[138] Buffon, the brilliant naturalist, whose work is one of the French classics, thus records his judgment:-- “All concurs to prove that the human race is not composed of species essentially different among themselves,--that, on the contrary, there was originally but a single species of men, who, in multiplying and spreading over all the surface of the globe, have undergone different changes through the influence of climate, difference of food, difference in the manner of living, epidemic maladies, and the infinitely varied intermixture of individuals more or less alike.”[139]