But Audubon had overcome obstacles before that, and three years later he issued the prospectus of his famous "Birds of America." It was to consist of four folio volumes of plates, and the price of each copy was fixed at a thousand dollars. Three years more were spent in securing subscriptions, and then the work of publication began, though Audubon had barely enough money to pay for a single issue. Funds came in, however, after the appearance of the first number, and the work went steadily forward to completion in 1839. It was called by the great naturalist, Cuvier, "the most magnificent monument that art ever raised to ornithology." It contained 448 beautifully colored plates, showing 1065 species of North American birds, each of them life size. Before it was completed, Audubon had planned another work on similar lines, to be known as "The Quadrupeds of America," and set to work at once to gather the necessary material, which meant the study from life of each of these animals. He even projected an extensive trip to the Rocky Mountains in search of material, but was pursuaded by his friends to give it up, as he was then nearly sixty years of age, and suffering from the effects of his long years of exposure. His sons assisted him in the preparation of the work, the first volume of which appeared in 1846, the last in 1854, three years after his death. Audubon's life illustrates strikingly the compelling power of devotion to an ideal. Few men have met such discouragements as he, and fewer still have overcome them. For many years, in all climates, in all weathers, pausing at no difficulty or peril, his life frequently endangered by wild beasts or still wilder savages, he trudged the pathless wilderness, quite alone, sleeping under a rude shelter of boughs or in a hollow tree, living on such game as he could shoot, seeking only one thing, new birds, and when he found them, observing their habits and setting them on paper with an infinite patience. On one occasion, rats got into the room where his drawings were stored, and destroyed almost all of them; but he set to work at once re-drawing them, where most men would have given up in despair. His work remains to this day the standard one on American birds--a mighty monument to the ideals of its maker. [Illustration: AGASSIZ]