The vessel sailed December 27, 1831. Though for a young man of an extremely affectionate nature the separation from family was painful, yet it was a glad day for Darwin. He had looked forward eagerly to it, saying, "My second life will then commence, and it shall be as a birthday for the rest of my life," and so it proved. He said, years afterward, "The voyage of the Beagle has been by far the most important event in my life, and has determined my whole career."

These years were busy, earnest ones, devoted to constant labor. To his father he wrote from Bahia, or San Salvador, the following spring: "No person could imagine anything so beautiful as the ancient town of Bahia; it is fairly embosomed in a luxuriant wood of beautiful trees, and situated on a steep bank, and overlooks the calm waters of the great Bay of All Saints. The houses are white and lofty, and, from the windows being narrow and long, have a very light and elegant appearance.... But the exquisite, glorious pleasure of walking amongst such flowers and such trees cannot be comprehended but by those who have experienced it.... I will not rapturize again, but I give myself great credit in not being crazy out of pure delight. Give my love to every soul at home.... I think one's affections, like other good things, flourish and increase in these tropical regions."

Again he writes from Rio de Janeiro: "Here (at Rio-Macoa) I first saw a tropical forest in all its sublime grandeur—nothing but the reality can give any idea how wonderful, how magnificent the scene is.... I never experienced such intense delight. I formerly admired Humboldt, I now almost adore him; he alone gives any notion of the feelings which are raised in the mind on first entering the Tropics. I am now collecting fresh-water and land animals.... I am at present red-hot with spiders; they are very interesting, and, if I am not mistaken, I have already taken some new genera." Busy as he was, he was ever thinking of home, and anxious to receive letters. When they were received, he almost "cried for pleasure."

He writes to his sister: "If you knew the glowing, unspeakable delight which I felt at being certain that my father and all of you were well, only four months ago, you would not grudge the labor lost in keeping up the regular series of letters."

Later he writes: "It is too delightful to think that I shall see the leaves fall and hear the robin sing next autumn at Shrewsbury. My feelings are those of a schoolboy to the smallest point; I doubt whether ever boy longed for his holidays as much as I do to see you all again."

To his "dear Henslow" he writes: "It is now some months since we have been at a civilized port; nearly all this time has been spent in the most southern part of Tierra del Fuego.... The Fuegians are in a more miserable state of barbarism than I had expected ever to have seen a human being. In this inclement country they are absolutely naked, and their temporary houses are like what children make in summer with boughs of trees."

Captain Fitz-Roy, on a previous voyage, had carried several natives to England, and now brought them again to their own land. "They had become," says Darwin, "entirely European in their habits and wishes, so much so that the younger one had forgotten his own language, and their countrymen paid but very little attention to them. We built houses for them, and planted gardens, but by the time we return again on our passage round the Horn, I think it will be very doubtful how much of their property will be left unstolen."

At the Cape of Good Hope, Darwin met and dined with Sir John Herschel. For some time he lived at St. Helena, "within a stone's throw of Napoleon's tomb." He became so deeply interested in his geological investigations in South America, that he wrote his sister Susan: "I literally could hardly sleep at nights for thinking over my day's work. The scenery was so new, and so majestic; everything at an elevation of twelve thousand feet bears so different an aspect from that in a lower country."

To another sister he wrote: "I trust and believe that the time spent in this voyage, if thrown away for all other respects, will produce its full worth in Natural History; and it appears to me the doing what little we can to increase the general stock of knowledge is as respectable an object of life as one can in any likelihood pursue.... What fine opportunities for geology and for studying the infinite host of living beings! Is not this a prospect to keep up the most flagging spirit? If I was to throw it away, I don't think I should ever rest quiet in my grave."

Darwin says: "As far as I can judge of myself, I worked to the utmost during the voyage, from the mere pleasure of investigation, and from my strong desire to add a few facts to the great mass of facts in natural science. But I was also ambitious to take a fair place among scientific men." In studying the geology of St. Jago, "It then first dawned on me that I might perhaps write a book on the geology of the various countries visited, and this made me thrill with delight. That was a memorable hour to me, and how distinctly I can call to mind the low cliff of lava beneath which I rested, with the sun glaring hot, a few strange desert plants growing near, and with living corals in the tidal pools at my feet. Later in the voyage, Fitz-Roy asked me to read some of my journal, and declared it would be worth publishing, so here was a second book in prospect!"