Nor was that all. The particular countries visited by the 'Beagle' during the course of her long and varied cruise happened to be exactly such as were naturally best adapted for bringing out the latent potentialities of Darwin's mind, and suggesting to his active and receptive brain those deep problems of life and its environment which he afterwards wrought out with such subtle skill and such consummate patience in the 'Origin of Species' and the 'Descent of Man.' The Cape de Verdes, and the other Atlantic islands, with their scanty population of plants and animals, composed for the most part of waifs and strays drifted to their barren rocks by ocean currents, or blown out helplessly to sea by heavy winds; Brazil, with its marvellous contrasting wealth of tropical luxuriance and self-strangling fertility, a new province of interminable delights to the soul of the enthusiastic young collector; the South American pampas, with their colossal remains of extinct animals, huge geological precursors of the stunted modern sloths and armadillos that still inhabit the self-same plains; Tierra del Fuego, with its almost Arctic climate, and its glimpses into the secrets of the most degraded savage types; the vast range of the Andes and the Cordilleras, with their volcanic energy and their closely crowded horizontal belts of climatic life; the South Sea Islands, those paradises of the Pacific, Hesperian fables true, alike for the lover of the picturesque and the biological student; Australia, that surviving fragment of an extinct world, with an antiquated fauna whose archaic character still closely recalls the European life of ten million years back in the secondary epoch: all these and many others equally novel and equally instructive passed in long alternating panorama before Darwin's eyes, and left their images deeply photographed for ever after on the lasting tablets of his retentive memory. That was the real great university in which he studied nature and read for his degree. Our evolutionist was now being educated.
Throughout the whole of the journal of this long cruise, which Darwin afterwards published in an enlarged form, it is impossible not to be struck at every turn with the way in which his inquisitive mind again and again recurs to the prime elements of those great problems towards whose solution he afterwards so successfully pointed out the path. The Darwinian ideas are all already there in the germ; the embryo form of the 'Origin of Species' plays in and out on every page with the quaintest elusiveness. We are always just on the very point of catching it; and every now and again we do actually all but catch it in essence and spirit, though ever still its bodily shape persistently evades us. Questions of geographical distribution, of geological continuity, of the influence of climate, of the modifiability of instinct, of the effects of surrounding conditions, absorb the young observer's vivid interest at every step, wherever he lands. He is all unconsciously collecting notes and materials in profuse abundance for his great work; he is thinking in rough outline the new thoughts which are hereafter to revolutionise the thought of humanity.