With a knowledge of the connexion between cause and effect is associated that of _power_. Give me where to stand, said Archimedes, and I could move the world. Man's natural powers are very limited, but his comprehensive mind enables him to overcome the most formidable obstacles; to bore through the mountain, to uproot it from its base, and scatter its fragments over the plain; to over-arch rivers and arms of the sea with iron pathways; to travel as rapidly as most birds fly; to upheave ponderous masses of stone, and to compress light and flocculent materials until they become solid and heavy. But man accomplishes all this and far more, not by his own bodily powers, but by machinery of various kinds, and of various degrees of simplicity or complexity; nay, he cannot even cultivate the soil, except by the aid of implements, that is, simple machines. Brutes entirely depend upon their own bodily powers, and gain a knowledge of the extent of those powers by experience. An old hunter will never attempt a leap which he knows he cannot accomplish--a young, fiery horse will make a dash at it, and perhaps fail; if he succeed, his dependence upon himself will be confirmed; on the other hand, should he not succeed, it is more than probable that he will lose all self-confidence, and therefore be henceforward useless for the chase. The elephant skilfully uses its tusks as levers, in the uprooting of trees; and when the megatherium and mylodon wrestled with the noblest productions of their primeval forests in South America, they applied in the best manner their forces and the means at their command. What is this but a knowledge (limited, we allow) of the relationship between cause and effect? The camel, when overladen, utters loud cries, and refuses to rise at the command of the driver; this was also a peculiarity of the llama, when that animal was exclusively the carrier of the Andes. With respect to a knowledge of power, as regards ourselves personally, or as displayed by brutes, we cannot help thinking that much depends on an _instinctive perception_, added to, no doubt, by experience. All animals, from man downwards, apply their force according to their conformation; the horse kicks--the lion strikes with his terrible paw--the hyena seizes with his jaw--man uses his arms; but man also brings art to aid him in his bodily exertions. Hence the strongest man falls under the skill of the trained wrestler; but the contest of brutes is that of force. Hence it is that man invents weapons which render the weak and the strong on a level, and which give to skill the predominance over force. This, too, implies a knowledge of the relationship between cause and effect, but a knowledge which brutes, if we except the chimpanzee, do not display. The chimpanzee, it is asserted, uses a club as a weapon, but we do not advance this as a fact positively established; indeed, we doubt it; we have never seen this animal use a stick, as we should use it in striking.