In the later years of this period some rays of improvement shone out. To end the reign of Owen's misleading types and imaginary archetypes, there arose a wielder of two potent words, "morphology" and "biology," the sciences of form and of life, who showed that differences of adult form grew out of likeness and simplicity in the young; and that the life of plants and animals was one science, their study one discipline. What Huxley had begun to proclaim from the housetop, Darwin was meditating in secret; and much more. Let us see how he states the case in the famous modest opening of the "Origin of Species" (1859): "When on board H.M.S. _Beagle_, as naturalist, I was much struck with certain facts in the distribution of the inhabitants of South America, and in the geological relations of the present to the past inhabitants of that continent. These facts seemed to me to throw some light on the origin of species--that mystery of mysteries, as it has been called by one of our greatest philosophers. On my return home, it occurred to me, in 1837, that something might perhaps be made out on this question by patiently accumulating and reflecting on all sorts of facts which could possibly have any bearing on it. After five years' work I allowed myself to speculate on the subject, and drew up some short notes; these I enlarged in 1844 into a sketch of the conclusions, which then seemed to me probable: from that period to the present day I have steadily pursued the same object. I hope that I may be excused for entering on these personal details, as I give them to show that I have not been hasty in coming to a decision." We learn also, independently, from the "Expression of the Emotions" (p. 19), that Darwin as early as 1838 was inclined to believe in the principle of evolution, or the derivation of species from other and lower forms.