\Sen*sa"tion\, n. [Cf. F. sensation. See {Sensate}.]
1. (Physiol.) 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.
2. A purely spiritual or psychical affection; agreeable or
   disagreeable feelings occasioned by objects that are not
   corporeal or material.
3. A state of excited interest or feeling, or that which
   causes it.
         The sensation caused by the appearance of that work
         is still remembered by many.          --Brougham.
Syn: Perception.
Usage: {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 produced 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.'' --Fleming.