In October 1838--that is, fifteen months after I had begun my systematic inquiry--I happened to read for amusement 'Malthus on Population'; and being well prepared to appreciate the struggle for existence which everywhere goes on from long-continued observation of the habits of animals and plants, it at once struck me that under these circumstances favorable variations would tend to be preserved, and unfavorable ones to be destroyed. The result of this would be the formation of new species. Here then I had at last got a theory by which to work; but I was so anxious to avoid prejudice that I determined not for some time to write even the briefest sketch of it. In June 1842 I first allowed myself the satisfaction of writing a very brief abstract of my theory in pencil in thirty-five pages; and this was enlarged during the summer of 1844 into one of two hundred and thirty pages, which I had fairly copied out and still possess. [Illustration: _THE APE-MAN_ Photogravure from a painting by Gabriel Max. Professor Max has long been known to the greater public through those wonderful pictures in which some tragic fate, some heart-break of mankind, has found expression; but only an inner circle of intimates has known the artist as an able student of nature. He has thought much and deeply upon the existence and origin of things; and his studies in comparative anatomy have given him unusual preparation for the treatment of the present subject. The entire picture is made up of yellowish and brownish-gray tones, expressive of the twilight of the forest. The skin of the female is about the shade of that of the Southern European of to-day; that of the male is darker. The most interesting of the three figures is the young ape-mother, who reclines against a tree-trunk and offers her breast to her first-born. The expression of the face is remarkable; happiness at the possession of the child mingles with misgiving for its future. The tear which trembles upon her cheek seems indicative of the flood of tears which is to run down the history of her descendants. The father has less of this feeling, and stands upright beside his wife and child and looks down upon them with an air of pride and paternal joy. The original painting is owned by the celebrated Darwinian philosopher Ernest Haeckel of Jena.]