Sensation the immediate effect produced on the mind by something acting upon the bodily organs. The earliest sign by which the Ego becomes perceptible is corporeal sensation, and this sensibility appears to be a necessary attribute of animated organic matter itself. All the perceptions of sense are rooted in the general sensation, which, however, is very obscure, even pain not being clearly felt by it at the place where it exists. The next step from this obscure, original, innate sensation is particular sensation, through the medium of the nervous system. Sensation should be distinguished from perception. The former properly expresses that change in the state of the mind which is produced by an impression upon an organ of sense; perception, on the other hand, expresses the knowledge or the intimations we obtain by means of our sensations concerning the qualities of matter. Sensation proper is not purely a passive state, but implies a certain amount of mental activity. It may be described, on the psychological side, as resulting directly from the attention which the mind gives to the affections of its own organism. Objection may be made that every severe affection of the body produces pain quite independently of any knowledge we may possess of the cause or of any operation of the will being directed towards it. Yet facts prove that if the attention of our minds be absorbed in other things, no impulse can produce in us the slightest feeling. Numerous facts prove that a certain application and exercise of mind, on one side, is as necessary to the existence of sensation as the occurrence of physical impulse, on the other. See Fleming, Vocab. of Philosophy, s.v.