and circumstance. Yet, observe the same bee exhausting herself by vain struggles against the sloping roof of a greenhouse, of which every window is thrown wide open. She perseveres, hour after hour, in unavailing endeavours to escape by her one accustomed upward track of flight, unable to conceive the possibility of transparent but impenetrable glass; and incapable of learning the fact by her repeated disappointments. In this way, hundreds of bees, butterflies, and other winged insects, perish miserably every summer. So, too, the highly educated and intelligent dog, will try to scratch holes in hard flag stones, and, after trials innumerable, still scratches on without seeming to discover that he never succeeds in making a single hole. Thus, also, birds in captivity keep up the perpetual motion of their heads--(useful to the poor prisoner no longer!) and generations after generations of captives maintain the instinctive practice. Numberless instances might easily be adduced to the same effect. But _no_ similar observation holds good of man. The child soon discontinues its efforts to thrust an arm through a glass window; and every day learns some new lesson in the properties of material objects. The engineer builds dams as well as the beaver;--but, beside dams, what marvels innumerable does he achieve with his earthworks, his timbers, and his stones! Speaking generally, we perceive that man has an instinctive tendency to lay hold of a practical fact, idea, and law of action, as a concrete whole;[163]--seizing it, at first, as the animal does without being able to analyze, recompound, or extend it. But reason holds the candle to instinct.[af] The impulse deepens and widens,--becomes distinguished by boldness and comprehensive breadth;--and it is difficult, if not impossible, to fix boundaries to its ultimate expansion. An expansion coextensive with the completed destinies of mankind.