_The Mind not complex._--Now mental activity is, strictly speaking, one and indivisible. The mind is not a complex substance, composed of parts, but single and one. Its activity may, however, be exercised in various ways, and upon widely different classes of objects; and as these modes of action vary, we may assign them different names, and treat of them in distinction from each other. So distinguished and named, they present themselves to us as so many distinct powers or faculties of the mind. But when this is done, and we make out, for purposes of science, our complete list and classification of these powers, we are not to forget that it is, after all, one and the same indivisible spiritual principle that is putting forth its activity under these diverse forms, one and the same force exerting itself--whether as thinking, feeling, or acting--whether as remembering, imagining, judging, perceiving, reasoning, loving, fearing, hating, desiring, choosing. And while we may designate these as so many faculties of the mind, we are not to conceive of them as so many constituent parts of a complex whole, which, taken together, compose this mysterious entity called the mind, as the different limbs and organs of the physical frame compose the structure called the body. Such is not the nature of the mind, nor of its faculties. _The Question before us._--In inquiring, then, what are the faculties of the mind, we have simply to inquire what are the distinct modes of its activity, what states and operations of the mind so far resemble each other as to admit of being classed together under the same general description and name. Our work, thus understood, becomes in reality a very simple one. _The more important Distinctions to be first ascertained._--What, then, are the clearly distinct modes of mental activity? And first let us endeavor to ascertain the wider and more important distinctions. We shall find that, innumerable as the forms of mental activity may at first sight appear, they are all capable of being reduced to a few general and comprehensive classes. _The first Form of mental Activity._--I sit at my table. Books are before me. I open a volume, and peruse its pages. My mind is occupied, its activity is awakened; the thoughts of the author are transferred to my mind, and engage my thoughts. Here, then, is one form of mental activity. This one thing I can do; this one power I have--the faculty of thought.