The Distinction, physiologically and psychologically considered, between Perception, Memory; Sensation, and Intellect
Authors: Davies W. G. 
Published: August 2008

Perception we define to be the intellectual and presentative consciousness of objects of any kind, internal or external, and the primary gateway of knowledge. In every perception the object is a most prominent feature. It is in the invariable presence of the object in perception, and its absence from memory and imagination, that we behold the striking difference which there is between it and the latter; and it is on this distinction the universal assurance is grounded that what we perceive is different from what we remember or imagine. In every perception there is an intellectual and a sensational element, and memory proper is the persistence of the intellectual element after the sensational element has disappeared from consciousness, or after the peripheral nerves have ceased to excite the sense-centre. In no instance have we been able, by any amount of effort, to make an act of memory or imagination seem a perception; yet Hume divided perceptions into two classes, as distinguished by their different degrees of force and vivacity. The less lively he named thoughts and ideas; the more lively, impressions. Professor Bain seems to take the same view of the question. In reference to the recalling of past feelings, he says:—“The renewed feeling occupies the very same parts, and in the same manner, as the original feeling, and no other parts, nor in any other manner that can be assigned.” It is the opinion of some, then, that memory and imagination only differ from perception in being less lively. The latter is a vivid picture, the former are faint reproductions of it. We fail to see that this is precisely the case. In every perception there is an object present, and cognized as distinct from the consciousness of it—in special instances, as even distinct from the perceiver altogether. When we gaze at a picture, the picture is regarded as one thing, the knowing of it as another; whereas when we only think of the picture, we do not recognize any object as really distinct from thought itself. An imagined external object is still detected to be a mental object. “A representation considered as an object is logically, not really, different from a representation considered as an act. Here object and act are merely the same indivisible mode of mind viewed in two different relations… The same may be said of image and imagination.” “Imagination, regarded as a product, may be defined, the consciousness of an image in the mind resembling and representing an object of intuition.” Though we do not exactly hold with these opinions, we quote them in order to show what view is taken by some psychologists in reference to the distinction between presentative and representative consciousness, or between knowing a thing immediately in perception, and knowing it mediately through an image of the mind's collecting. How is it possible, when contemplating a mountain which one is on the point of ascending—albeit the mountain is to us, as immediately known, in a sense-centre—to regard it as identical, except in vivacity, with the recollection which we afterwards have of it? Perception is, so to speak, a bi-une fact, a synthesis of cognition and object, whereas memory and imagination are not bi-une, for the object is not present in them, in the same manner, at least, as it is in perception. But let us now proceed to adduce facts and deductions confirmatory of this view of the question.