But when we consider that the higher animals can compare objects and make selections, exercise a memory and have association of ideas concerning each other and the outer world, we come near to that human quality which is the ground of the function of laughter. These mental traits are the buried roots of the consciousness which blossoms into smiles in the sun of wit and humor. For the power to combine or to contrast two or more objects, to remember one absent object by another present one, to experience a feeling that two objects are associated, leads to the highest manifestations of wit. In the delicate structures of men and women, which are bequests to them descending through the whole inviolate entail of Nature, refined by it and amplified till they entertain keenly the pathos of life, all mental traits accumulate into the faculty of imagination, upon which every thing that is laughable depends.
With this faculty man makes shift to relieve the moments when existence, with its incessant toil and merciless persistency of routine, threatens to become insupportable. One day is not exactly like another, if hearty laughter loosens its handcuffs and lets the prisoner stretch his frame and have a little run. Every laugh reddens the blood, which goes then more blithely to dissipate the fogs of a moody brain. Multitudes of our American brains are badly drained in consequence of a settling of the wastage of house-grubbing and street-work into moral morasses which generate many a chimera. So there is something positively heroic in the hilarity which braves, light-armed as it is, our brood of viperous cares, and attacks their den. One flash of a smile shears off Medusa's head with impunity.
No creature that is not capable of being bored can be capable of laughing at its own incongruous circumstances. The more simply constructed the brain and nervous system are, the less liability is there to that misfortune of _ennui_. We cannot imagine that a turtle's head gets tired of lying around, decapitated, for a week or more; or that a toad imprisoned in a rock or tree for one or two thousand years should become jaded by its close confinement. When the miner's pick releases him, his hop is as alert, and his appetite for the next fly as keen, as before his prison stole upon him. The lower animals are as contented as the forests and waters in which they pass an instinctive existence. Continually cheerful we may suppose they are, even when the larder is empty and the springs run low. Their monotonous round of hungering, feeding, and procreating sympathizes with the reposeful temper in which the whole of the inanimate nature discharges those functions, as we see the flower absorb, fructify, and exhale. But as the brain becomes more complicated, and capable of breeding more positive ideas and feelings,--such as the questing of a greyhound, the tact of setters and retrievers, the attachment of dogs for persons,--we may expect to observe a liability to suffer tedium. How plainly a good dog can show his disappointment when he goes out with a green sportsman, or with one who is so abstracted in his mood that he neglects the chances to shoot! The dog's natural language is that he will not tolerate such an irreligious abuse of providence: he will soon begin to sulk and not put up any more game.