(Islands are almost as prominent in the story of evolution as they are in the story of adventure. There are Robinson Crusoes until you can't rest!) How the pig in the struggle of life won out as usual. Why the peacock has such a fine tail and how he overdid it. How the elephant saved his life by lengthening his nose. How the birds traded their teeth for feathers. How shelled creatures coiled and uncoiled their shells. Why we miss the "missing links." (As you go into this subject of evolution you will hear a good deal about missing links.) How they know butterfly wings are made first and the coloring and patterns laid on afterward. How much of a butterfly's beauty is probably known to the butterflies themselves. How Nature seems to make things just to be pretty. And these are just a few of the things in _one_ of Doctor Wallace's books.[60] [Footnote 60: In addition to all this curious and absolutely reliable information that ought to be interesting to every one is the fact that Wallace shows in "The World of Life" how there must have been Mind and Purpose back of it all. Doctor Wallace was a great traveller as well as a great student of nature--one of the most famous in the history of science. His works include: "Travels on the Amazon and the Rio Negro," "The Malay Archipelago," "Natural Selection," "Darwinism," "Island Life and the Geographic Distribution of Animals." There are so many books on this biggest of all nature topics--Evolution--that they make quite a library in themselves. The most famous of these books is Darwin's "Origin of Species," and it is not at all hard to understand. Other books bearing directly or indirectly on evolution are "Animals of the Past," by Lucas, "Creatures of Other Days," by Hutchinson, Fiske's "Destiny of Man," and "Evolution and Religion." A book for older readers--one of the latest and most comprehensive treatments of the subject--is Osborn's "Origin and Evolution of Life."] Then he was such a fine man personally. Why, what do you think he did? Although he thought out the principle of evolution independently of Darwin, and wrote an essay on it before Darwin had ever given his views to the world, yet after Darwin's "Origin of Species"[61] came out Wallace gave Darwin all the credit, and in his own autobiography always referred to the theory of evolution as the "Darwinian Theory." Yet Wallace had a very good reason for taking this generous attitude, as you will see from his autobiography and other writings, and you are quite likely to find the reason in articles on Darwin or Wallace or Evolution. [Footnote 61: Of "The Origin of Species" it has been said that no work ever produced so profound a change in the opinions of mankind.] The relations of Darwin and Wallace furnish one of the finest examples in history of the best thing in the world--human friendship.