1. (Science: physiology) An impression, or the consciousness of an impression, made upon the central nervous organ, through the medium of a sensory or afferent nerve or one of the organs of sense; a feeling, or state of consciousness, whether agreeable or disagreeable, produced either by an external object (stimulus), or by some change in the internal state of the body. Perception is only a special kind of knowledge, and sensation a special kind of feeling. . . . Knowledge and feeling, perception and sensation, though always coexistent, are always in the inverse ratio of each other. (Sir W. Hamilton)
Sensation, Perseption. The distinction between these words, when used in mental philosophy, may be thus stated; if I simply smell a rose, I have a sensation; if I refer that smell to the external object which occasioned it, I have a perception. Thus, the former is mere feeling, without the idea of an object; the latter is the mind's apprehension of some external object as occasioning that feeling. Sensation properly expresses that change in the state of the mind which is pr 7bd oduced by an impression upon an organ of sense (of which change we can conceive the mind to be conscious, without any knowledge of external objects). Perception, on the other hand, expresses the knowledge or the intimations we obtain by means of our sensations concerning the qualities of matter, and consequently involves, in every instance, the notion of externality, or outness, which it is necessary to exclude in order to seize the precise import of the word sensation. .
Origin: Cf. F. Sensation. See Sensate.