His testimony that Mr. Darwin's doctrine excludes all teleology, or final causes, is explicit. In his review of the "Criticisms on the Origin of Species," he says, "that when he first read Mr. Darwin's book, that which struck him most forcibly was the conviction that teleology, as commonly understood, had received its death-blow at Mr. Darwin's hands. For the teleological argument runs thus: An organ is precisely fitted to perform a function or purpose; therefore, it was specially constructed to perform that function. In Paley's famous illustration, the adaptation of all the parts of a watch to the function or purpose of showing the time, is held to be evidence that the watch was specially contrived to that end; on the ground that the only cause we know of competent to produce such an effect as a watch which shall keep time, is a contriving intelligence adapting the means directly to that end."[24] This, Mr. Huxley tells us, is precisely what Darwin denies with reference to the organs of plants and animals. The eye was not formed for the purpose of seeing, or the ear for hearing. It so happened that a nerve became sensitive to light; then in course of time, it happened that a transparent tissue came over it; and thus in "millions of years" an eye, as we have seen above, happened to be formed. No such organ was ever intended or designed by God or man. "An apparatus," says Professor Huxley, "thoroughly adapted to a particular purpose, might be the result of a method of trial and error worked by unintelligent agents, as well as by the application of means appropriate to the end by an intelligent agent." "For the notion that every organism has been created as it is and launched straight at a purpose, Mr. Darwin substitutes the conception of something, which may fairly be termed a method of trial and error. Organisms vary incessantly; of these variations the few meet with surrounding conditions which suit them, and thrive; the many are unsuited, and become extinguished." "For the teleologist an organism exists, because it was made for the conditions in which it is found; for the Darwinian an organism exists, because, out of many of its kind, it is the only one which has been able to persist in the conditions in which it is found." "If we apprehend," Huxley further says, "the spirit of the 'Origin of Species' rightly, then, nothing can be more entirely and absolutely opposed to teleology, as it is commonly understood, than the Darwinian theory." (p. 303)