Unlike dogs, raccoons, or squirrels, chained monkeys rarely entangle themselves: they at once notice the shortening of their tether, and never rest till they have discovered the clue of the phenomenon. A dog in the same predicament has to content himself with tugging at his chain or gnawing his rope; and the reason is that the wisdom of the wisest dog is limited to business qualifications. He is a hunter, and nature has endowed him with the requisite faculties, just as she has endowed the constructive spider and the bee. Bees and dogs share the faculty of direction, enabling them to find their way home, a talent implying a very miracle of infallible and yet unconscious intuition, and in the strictest sense a one-sided business qualification. The goose, the sturgeon, and the almost brainless tortoise possess the same gift in a transcendent degree; the oriole builds her first nest as skilfully as the last; the young bee constructs her hexagons with an ease and a uniform success that leave no possible doubt that the exercise of her talent is generically different from a function of reason. Instincts may be far-reaching enough to defy the rivalry of human science, but they resemble loophole-guns, that can be fired only in a single direction. The intuition that guides the turkey-hen to her nest does not enable her to find her way out of a half-open log trap. The instinct by which a dog retraces his trail across broad rivers and through woods does not enable him to retrace the coils of a tangled rope. A monkey's talents, like our own, are less infallible, but more versatile, and at the possessor's discretion can be applied and perverted to all possible purposes. Hence also that peculiar interest which the pranks of our mischievous relatives excite even in spectators not apt to appreciate the comic features of the spectacle. In the monkey-house of the Philadelphia Zoo I have seen saturnine burghers stand motionless for hours together, and contemplative children rapt in reveries that had little to do with the hope of witnessing a beast-fight. They seemed to feel the spell of a secret veiled in grotesque symbols, but disclosing occasional revelations of its significance, like glimpses into the fore-world of the human race.