3. The highest class of ideas, which psychologists are unanimous in denying to brutes, and which, therefore, we are justified in regarding as the unique prerogative of man. These are the General, Abstract, and Notional ideas of Locke, or the Concepts just mentioned in the last paragraph. As we have there seen, they differ from recepts—and, _a fortiori_, from percepts, in that they are themselves the objects of thought. In other words, it is a peculiarity of the human mind that it is able to think about its own ideas as such, consciously to combine and elaborate them, intentionally to develop higher products out of less highly developed constituents. This remarkable power we found—also by common consent—to depend on the faculty of self-consciousness, whereby the mind is able, as it were, to stand apart from itself, to render one of its states objective to others, and thus to contemplate its own ideas as such. Now, we are not concerned with the philosophy of this fact, but only with its history. How it is that such a faculty as self-consciousness is possible; what it is that can thus be simultaneously the subject and the object of thought; whether or not it is conceivable that the great abyss of personality can ever be fathomed; these and all such questions are quite alien to the scope of the present work. All that we have here to do is to analyze the psychological conditions out of which, as a matter of observable fact, this unique peculiarity emerges—to trace the history of the process, and tabulate the results. Well, we have seen that here, again, every one agrees in regarding the possibility of self-consciousness to be given in the faculty of language. Whether or not we suppose that these two faculties are one—that neither could exist without the other, and, therefore, that we may follow the Greeks in assigning to them the single name of Logos,—at least it is as certain as the science of psychology can make it, that within the four corners of human experience a self-conscious personality cannot be led up to in any other way than through the medium of language. For it is by language alone that, so far as we have any means of knowing, a mind is rendered capable of so far fixing—or rendering definite to itself—its own ideas, as to admit of any subsequent contemplation of them as ideas. It is only by means of marking ideas by names that the faculty of conceptual thought is rendered possible, as we saw at considerable length in Chapter IV.