"Most of the 1300 millions of the earth's inhabitants have either a scanty nourishment, unsatisfying and prolonging life with difficulty, or they live for a time in superfluity, from which they derive no preponderating enjoyment, and must for another period actually starve and suffer want, when they must accordingly endure the pains of hunger for long periods, whilst the pleasure of satiety, with perfect stilling of hunger, only occupies a few hours of the day. But now let any one compare the dull delight of satiety and digestion with the distinct gnawing of hunger or the hell-torments of thirst to which animals in deserts, steppes, and such regions, that in the hot season are perfectly dry, are not seldom exposed. How much more, however, must among many species of animals the pain of hunger exceed the pleasure of satiety in the course of life, which at certain seasons die of hunger from want of food, often in considerable numbers, or for weeks and months just on the brink of starvation, prolong their existence in slightly more favourable conditions of life! This happens both with graminivorous birds and birds in the winter of the polar and temperate zones and in the arid tropics, as also with carnivora and beasts of prey, which often for weeks wander about vainly in search of booty until they perish of inanition."