Page:The System of Nature.djvu/147

 which it is agitated in its peculiar operations, from which it imbibes new perceptions and new ideas. It is the exercise of this power to fall back upon itself, that is called reflection.

From this it will appear, that for man to think and to reflect, is to feel, or perceive within himself the impressions, the sensations, the ideas, which have been furnished to his brain by those objects which give impulse to his senses, with the various changes which his brain produced on itself in consequence.

Memory is the faculty which the brain has of renewing in itself the modifications it has received, or rather, to restore itself to a state similar to that in which it has been placed by the sensations, the perceptions, the ideas, produced by exterior objects, in the exact order it received them, without any new action on the part of these objects, or even when these objects are absent; the brain perceives that these modifications assimilate with those it formerly experienced in the presence of the objects to which it relates, or attributes them. Memory is faithful, when these modifications are precisely the same; it is treacherous, when they differ from those which the organs have exteriorly experienced.

Imagination in man is only the faculty which the brain has of modifying itself, or of forming to itself new perceptions, upon the model of those which it has anteriorly received through the action of exterior objects on the senses. The brain, then, does nothing more than combine ideas which it has already formed, which it recalls to itself, from which it forms a whole, or a collection of modifications, which it has not received, which exists no-where but in itself, although the individual ideas, or the parts