His "Voyage of the Beagle" alone would insure him lasting fame. It is a classic among scientific books of travel. Here is a traveler of a new kind: a natural-history voyager, a man bent on seeing and taking note of everything going on in nature about him, in the non-human, as well as in the human world. The minuteness of his observation and the significance of its subject-matter are a lesson to all observers. Darwin's interests are so varied and genuine. One sees in this volume the seed-bed of much of his subsequent work. He was quite a young man (twenty-four) when he made this voyage; he was ill more than half the time; he was as yet only an observer and appreciator of Nature, quite free from any theories about her ways and methods. He says that this was by far the most important event of his life and determined his whole career. His theory of descent was already latent in his mind, as is evinced by an observation he made about the relationship in South America between the extinct and the living forms. "This relationship," he said, "will, I do not doubt, hereafter throw more light on the appearance of organic beings on our earth, and their disappearance from it, than any other class of facts." He looked into the muddy waters of the sea off the coast of Chile, and found a curious new form of minute life--microscopic animals that exploded as they swam through the water. In South America he saw an intimate relationship between the extinct species of ant-eaters, armadillos, tapirs, peccaries, guanacos, opossums, and so on, and the living species of these animals; and he adds that the wonderful relationship in the same continent between the dead and the living would doubtless hereafter throw more light on the appearance of organic beings on our earth, and their disappearance from it, than any other class of facts. His observation of the evidences of the rise and fall of thousands of feet of the earth along the Cordilleras leads him to make this rather startling statement: "Daily it is forced home on the mind of the geologist that nothing, not even the wind that blows, is so unstable as the level of the crust of the earth." There is now and then a twinkle of humor in Darwin's eyes, as when he says that in the high altitude of the Andes the inhabitants recommend onions for the "puna," or shortness of breath, but that he found nothing so good as fossil shells. Water boils at such a low temperature in the high Andes that potatoes will not cook if boiled all night. Darwin heard his guides discussing the cause. "They had come to the simple conclusion that 'the cursed pot' (which was a new one) did not choose to boil potatoes." In all Darwin's record we see that the book of nature, which ordinary travelers barely glance at, he opened and carefully perused. V