— 144 —
      §4. How often may a Man observe in himself, that whilst his
Mind is intently employ’d in the contemplation of some Objects;
and curiously surveying some Ideas that are there, it takes no notice
of impressions of sounding Bodies, made upon the Organ of Hearing,
with the same alteration, that uses to be for the producing the Idea
of a Sound? A sufficient impulse there may be on the Organ; but it
not reaching the observation of the Mind, there follows no per-
ception: And though the motion, that uses to produce the Idea of
Sound, be made in the Ear, yet no sound is heard. Want of Sen-
sation in this case, is not through any defect in the Organ, or that
the Man’s Ears are less affected, than at other times, when he does
hear: but that which uses to produce the Idea, though conveyed in
by the usual Organ, not being taken notice of in the Understanding,
and so imprinting no Idea on the Mind, there follows no Sensation.
So that where-ever there is Sense, or Perception, there some Idea is actually
produced, and present in the Understanding.
Locke Hum II, 9, §4, p. 144