Nevertheless, thought does not originate in the total absence of imagery, but requires a minimal substrate of sensible images, upon which it is objectively, if not subjectively, dependent. The nature of this objective dependence is explained by the Scholastic theory concerning the origin of concepts. According to this theory, the genesis of our general and abstract knowledge is as follows: (1) We begin with sense-perception, say of boats differing in shape, size, color, material, location, etc. (2) Imagination and sense-memory retain the composite and concrete imagery synthesized or integrated from the impressions of the separate external senses and representing the boats in all their factual particularity, individuality, and materiality, as existent here and now, or there and then, as constructed of such and such material (_e.g._, of wood, or steel, or iron, or concrete), as having determinate sizes, shapes, and tonnages, as painted white, or gray, or green, as propelled by oar, or sail, or turbine, etc. (3) Then the _active intellect_ exerts its abstractive influence upon this concrete imagery, accentuating the essential features which are common to all, and suppressing the individuating features which are peculiar to this or that boat, so that the essence of a boat may appear to the _cognitive intellect_ without its concomitant individuation—the essence of a boat being, in this way, isolated from the peculiarities thereof and its various qualities from their subject (representatively, of course, and not physically). (4) The imagery thus predisposed, being no longer immersed in matter, but dematerialized by the dispositive action of the active intellect, becomes coïnstrumental with the latter in producing a determination in the cognitive intellect. (5) Upon receiving this determination, the cognitive intellect, which has hitherto been, as it were, a blank tablet with nothing written upon it, reacts to express the essence or nature of a boat by means of a spiritual representation or concept—the abstractive act of the active intellect is _dispositive_, inasmuch as it _presents_ what is common to all the boats perceived without their differentiating peculiarities; the abstractive act of the cognitive intellect, however, is _cognitive_, inasmuch as it _considers_ the essence of a boat without considering its individuation. Such is the abstractive process by which our general and abstract concepts are formed. From a comparison of two concepts of this sort the process of judgment arises, and from the comparison of two concepts with a third arises the process of mediate inference or reasoning. Volition, too, is consequent upon conception, and hence an act of the will (our rational appetite), such as the desire of sailing in a boat, entails the preëxistence of some conceptual knowledge of the nature of a boat. Volition, therefore, presupposes thought, and thought presupposes imagination, which