4. Impulse on the organ insufficient.
How often may a man observe in himself, that whilst his mind is intently
employed 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 sound? A sufficient impulse there may be on the organ; but it not reaching the
observation of the mind, there follows no perception: and though the motion that uses to produce the idea of
sound be made in the ear, yet no sound is heard. Want of sensation, 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 in the mind, there follows no sensation. So that wherever there is sense or perception, there
some idea is actually produced, and present in the understanding.
