It's a bit overwhelming "reviewing" this book. There is so much to say, and yet the words seem inadequate. It is a brilliant piece of work that was meticulously researched and written. Darwin did not simply state his brilliant insights concerning how species evolve through natural selection, how new species can be "created" by this process, and how all organisms on earth are related in a huge "tree of life". He also discussed alternatives to these hypotheses, problems raised by the hypotheses, inadequacies of these hypotheses, and ultimately, how these hypotheses compare to the predominant idea of the time, which was that species were individual acts of creation by a deity. If all the man wrote about was natural selection, the book would have been brilliant. But, by throwing in the origin of species and the common ancestry of all life (descent through modification), he really wrote one of the most, if not the most, important books on biology ever.
I loved each and every chapter, but my favorite was the one about geographical distribution. He discussed how species came to be where they are. Creationism states that god put them there in current form. Darwin thought that this made God one busy micromanager. Darwin thought seeds could float from mainland to islands. He even tested this by soaking seeds in ocean water for a month and then planting them to prove that they were still viable. (My class is currently repeating this experiment). He thought that mollusc (snail, clam, etc) larvae could be transported on duck feet. He also tested this. He thought mud on duck feet could transport seeds as well (which he also tested!). I loved his idea of how seeds could be transported to distant islands because fish eat seeds, birds then eat the fish, and then the bird will defecate the seeds on the island (he did not test this idea, however!).
It is an excellent persuasive essay, or "one long arguement" as he put it. At one point in the book he asked "does my theory or their theory explain these facts?" Well, if you ask me, yours does, Darwin.