It is true, that we often see in the inferior animals manifestations of deductions of intellect similar to those of the human mind,--only that they are not made by the animals themselves, but for them and above their conscious perception. "When a bee," says Dr. Reid, "makes its combs so geometrically, the geometry is not in the bee, but in that great Geometrician who made the bee, and made all things in number, weight, and measure." Since the animal is not conscious of the intelligence and design which are manifested in its instincts, which it obeys and works out, the conscious life of the individual must be wholly a life within the senses. The senses alone can give the animal only an empirical knowledge of the world of its observation. The senses may register and report facts, but they can never arrive at an understanding of necessary truths; the source of this kind of knowledge is the rational mind, which has an active disposition to draw out these infallible laws and eternal truths from its own bosom. The main tendency of the rational mind is not towards mere phenomena, but their scientific explanation. It seeks to trace effects, as presented to us by the senses, back to the causes which produced them; or contemplating things wholly metaphysical, it seeks to follow out the laws which it has itself discovered, till they have gone through a thousand probable contingencies and lost themselves in numberless results. It is on account of this capacity and tendency of the human mind to look through fact to law, through individuals to classes, through effects to causes, through phenomena to general principles, that the late Dr. Burnap was led to declare, in a very interesting course of lectures which he delivered before the Lowell Institute a few years since, that he considered the first characteristic difference between the highest species of animals and the lowest race of man to be a capacity of science. But is not the whole edifice of human science built upon the simple faculty of comparison? This is the ultimate analysis of all the highest manifestations of the human mind, whether of judgment, or reason, or intellect, or common sense, or the power of generalization, or the capacity of science. We have already quoted Hamilton to this effect, and we, moreover, have his authority for saying that the faculty of discovering truth, by a comparison of the notions we have obtained by observation and experience, is the attribute by which man is distinguished as a creature higher than the animals. We might also cite Leibnitz to the effect that men differ from animals in being capable of the formation of necessary judgments, and hence capable of demonstrative sciences.