As to the understanding--in one of the earliest of these Lectures, we mentioned abstract thought as its peculiar form of error. It is unquestionable that the understanding may lose itself in mere abstract and dead thinking, so as, amid its mass of purely abstract conceptions, to forget entirely all truly pregnant and vital cogitation. Such as understanding, there can be no doubt, must either be defective in its organization, or imperfectly and falsely developed; and so it goes on deceiving itself and propagating error among others. Correctly speaking, however, this abstract thinking does not belong to the understanding, so much as to the reason, which is even the faculty of abstraction. And indeed, apart from its great and manifold abuses, the latter, in its right place and within its assigned limits, forms nothing less than a natural requirement and an essential function of the human mind. As for the understanding, it is based on intellection; consequently it supposes that in this intellectual act the object is vividly seen through and thoroughly penetrated by the mind. And this object may be either an external one, taken from nature or actual life, or internal--a mere thought or conception, and the word or name designating it. In the latter case, the mental act of penetration is directed to ascertaining the true and original sense of an idea, or the import of the notion, or of the term by which it is designated. An understanding which has lost itself among abstract ideas must, in such purely abstract thinking, become eventually entirely extinct. Wholly, however, without life and spirit, the understanding, according to its peculiar character, can never be; it is therefore its total absence, or a very defective condition of it, rather than its death, that is marked out and indicated by such a state. But if we wish to determine the particular fault or error that is peculiar to any one faculty of the human consciousness, it is evident that we must not seek for it in any defective state or imperfect development; but, on the contrary, in the highest and fullest energy. But now an extremely ingenious, clear, and vivid intellect may be combined with what I have lately termed an evil genius--the false power of genius. In such a combination, we have the true state of a perverted understanding, or of that aberration which is peculiar to it, and for which the term of a sophistical intellect seems the tersest and most appropriate designation. And this sophistical understanding is ever the working organ and instrument for the building and construction of all false systems, and to which sooner or later the latter are all obliged to have recourse.