All our passions appear to claim the respiratory nerves for outward expression. They are a signal corps which communicate by hoisting the blush, the smile; by letting fall the tear, by the exhalation of a sigh, by the explosions of laughter. The life-breaths of joy and grief tend primitively to the lungs, and they voice the mother-tongue of all emotions.
I have often wondered how animals can avoid being struck with the differences which exist among themselves, so much more salient and intrusive than among the races of men, in shape, gestures, tones, and habits. What a wide range of Nature's curious freakery a forest has, or a district of country like those plains and thickets of Africa, where the natives dig their great pit and organize a monster drive! Into it falls every thing which cannot escape to either side. The giraffe, elephant, gnu, antelope, hartbeest, zebra, jackal,--think of the commingling of strange discrepancies thus suddenly collected! Were it not for the panic which prevails, and the accidents to life and limb, one would suppose that they ought to be aware of Nature's whims in themselves, and to narrowly escape inventing amusement. But curiosity and aversion probably exhaust the speculative possibilities of animals in this direction.
It is true, we occasionally hear of happy families, like that of the prairie-dog who has an owl and a rattlesnake to share his housekeeping, which they do with zest; for they have established a taste for the young of the prairie-dog, and they hire his tenement only with an eye to business.
When a great freshet takes possession of a country, and evicts the tenants of every hole, thicket, and burrow, there is an indiscriminate stampede of the animals for the driest and safest places: hares, rattlesnakes, mice, cats, and the carnivora cling together to the tops of trees, or wait in terror on the highest hills. So a prairie fire startles all the wild creatures with its sweep into a promiscuous race towards some spot that cannot be tenanted by flame. There they might observe the strange traits which shun each other in ordinary times or seek each other only when hunger demands its toll. While the fright and the dread of death are beginning to pass off are these creatures insensibly attracted to notice each other? Probably only as a curious deer observes a man. The danger has not established any sympathy between them. And they separate without any better opinion of each other, nor approach to geniality. Even men who are strangers, and in general dissociated by the distinctions of society, will be thrown together by some stress of the moment, part with a mutual feeling of relief, and resume their predilections. Yet man only is endowed with the magnanimity to welcome the emergencies which abolish superficial differences. They can be invaded by a circumstance which comprises them under an idea different from those which keep them asunder; and this new congruity can make the forced society congenial. It is Nature's witty rendering of the text that declares all men of one blood. The effect is grave, and under some conditions it may reach an heroic stature, but the root of wit is the nourisher; and only those creatures who are capable of annihilating capricious distinctions by a feeling of common humanness are capable of enjoying the union of heterogeneous ideas.