Page:The System of Nature.djvu/145

 man during the presence of any object whatever. Suppose for a moment this object to be a peach: this fruit makes, at the first view, two different impressions on his eyes; that is to say, it produces two modifications, which are transmitted to the brain, which on this occasion experiences two new perceptions, or has two new ideas or modes of existence, designated by the terms colour and rotundity; in consequence, he has an idea of a body possessing roundness and colour: if he places his hand on this fruit, the organ of feeling having been set in action, his hand experiences three new impressions, which are called softness, coolness, weight, from whence result three new perceptions in the brain, he has consequently three new ideas: if he approximates this peach to his nose, the organ of smelling receives an impulse, which, communicated to the brain, a new perception arises, by which he acquires a new idea, called odour: if he carries this fruit to his mouth, the organ of taste becomes affected in a very lively manner: this impulse communicated to the brain, is followed by a perception that generates in him the idea of flavour. In re-uniting all these impressions, or these various modifications of his organs, which it have been consequently transmitted to his brain; that is to say, in combining the different sensations, perceptions, and ideas, that result from the impulse he has received, he has an idea of a whole, which he designates by the name of a peach, with which he can then occupy his thoughts.

From this it is sufficiently proved that thought has a commencement, a duration, an end; or rather a generation, a succession, a dissolution, like all the other modifications of matter; like them, thought is