But what is this essential difference between man and the brute? The most simple, general, and also the most popular answer to this question is--consciousness:--but consciousness in the strict sense; for the consciousness implied in the feeling of self as an individual, in discrimination by the senses, in the perception and even judgment of outward things according to definite sensible signs, cannot be denied to the brutes. Consciousness in the strictest sense is present only in a being to whom his species, his essential nature, is an object of thought. The brute is indeed conscious of himself as an individual--and he has accordingly the feeling of self as the common centre of successive sensations--but not as a species: hence, he is without that consciousness which in its nature, as in its name, is akin to science. Where there is this higher consciousness there is a capability of science. Science is the cognisance of species. In practical life we have to do with individuals; in science, with species. But only a being to whom his own species, his own nature, is an object of thought, can make the essential nature of other things or beings an object of thought. Hence the brute has only a simple, man a twofold life: in the brute, the inner life is one with the outer; man has both an inner and an outer life. The inner life of man is the life which has relation to his species, to his general, as distinguished from his individual, nature. Man thinks--that is, he converses with himself. The brute can exercise no function which has relation to its species without another individual external to itself; but man can perform the functions of thought and speech, which strictly imply such a relation, apart from another individual. Man is himself at once I and thou; he can put himself in the place of another, for this reason, that to him his species, his essential nature, and not merely his individuality, is an object of thought.