The dialectical faculty of abstraction is naturally the predominant one, and the most completely evolved in the thinking mind. Accordingly, most thinkers have set it up as the basis of their speculations, in order to arrive the more rapidly at the desired end of an absolute science; or, if the habit of mind be more disposed that way, at an absolute _not-knowing_, and the rejection of all certainty; which, in the main, is quite as false, and, in this respect, identical with the former. But it is not sufficient to follow any such a partial course, and to start from any one side merely of the human consciousness. On the right and sure road of a complete and thorough investigation, our first duty is to study the human consciousness in its fullness and living development, in all its faculties and powers. And then, in the second place, when, by thus assuming a position in the center, man has enabled himself to take a complete survey of the whole, he may unquestionably proceed to inquire what kind and what degree of knowledge, with such a consciousness, he is capable of attaining, both of the external world and of the suprasensible, and how far the latter is conceivable and its existence possible. Now, just as generally the soul is the principle of all life in nature, so is the thinking soul the center of the human consciousness. But in the thinking soul is comprised the reason which distinguishes, combines, and infers, no less than the fancy which devises, invents, and suggests. Standing in the center between the two, the thinking soul embraces both faculties. But it also forms the turning-point of transition between the understanding and the will; and, as the connecting link, fills up the gulf which otherwise would lie between and divide the two. It comprises, also, all sorts and degrees of conceptions, from the absolutely necessary, precisely definite, and permanently unchangeable, down to those which arise and pass away half involuntarily--from those in no degree clearly developed up to those which have been advanced to the highest clearness of the understanding--those which are witnessed with a calm indifference, and those also which excite a gentle longing or kindle a burning resolve. The thinking soul is the common store-house where the whole of these conceptions are successively lodged. Indeed, to describe it in general terms, it is but the inner pulse of thought, corresponding to the pulsation of the blood in the living body.