. In the next place,  are to be considered.
And, with regard to these, I would fain know whether what hath
{181} been said of tastes doth not exactly agree to them? Are
they not so many pleasing or displeasing sensations?

     . They are.

     . Can you then conceive it possible that they should
exist in an unperceiving thing?

     . I cannot.

     . Or, can you imagine that filth and ordure affect
those brute animals that feed on them out of choice, with the
same smells which we perceive in them?

     . By no means.

     . May we not therefore conclude of smells, as of the
other forementioned qualities, that they cannot exist in any but
a perceiving substance or mind?

     . I think so.

     . Then as to , what must we think of them: are
they accidents really inherent in external bodies, or not?

     . That they inhere not in the sonorous bodies is plain
from hence: because a bell struck in the exhausted receiver of an
air-pump sends forth no sound. The air, therefore, must be
thought the subject of sound.

     . What reason is there for that, Hylas?

     . Because, when any motion is raised in the air, we
perceive a sound greater or lesser, according to the air's
motion; but without some motion in the air, we never hear any
sound at all.

     . And granting that we never hear a sound but when
some motion is produced in the air, yet I do not see how you can
infer from thence, that the sound itself is in the air.

     . It is this very motion in the external air that
produces in the mind the sensation of . For, striking on
the drum of the ear, it causeth a vibration, which by the
auditory nerves being communicated to the brain, the soul is
thereupon affected with the sensation called .

     . What! is sound then a sensation?

     . I tell you, as perceived by us, it is a particular
sensation in the mind.

     . And can any sensation exist without the mind?

     . No, certainly.

     . How then can sound, being a sensation, exist in the
air, if by the  you mean a senseless substance existing
without the mind?

     . You must distinguish, Philonous, between sound as it
is {182} perceived by us, and as it is in itself; or (which is
the same thing) between the sound we immediately perceive, and
that which exists without us. The former, indeed, is a particular
kind of sensation, but the latter is merely a vibrative or
undulatory motion the air.

     . I thought I had already obviated that distinction,
by answer I gave when you were applying it in a like case before.
But, to say no more of that, are you sure then that sound is
really nothing but motion?

     . I am.

     . Whatever therefore agrees to real sound, may with
truth be attributed to motion?

     . It may.

     . It is then good sense to speak of  as of a
thing that is , , , .

     .  see you are resolved not to understand me. Is it
not evident those accidents or modes belong only to sensible
sound, or  the common acceptation of the word, but not
to  in the real and philosophic sense; which, as I just
now told you, is nothing but a certain motion of the air?

     . It seems then there are two sorts of sound -- the
one vulgar, or that which is heard, the other philosophical and
real?

     . Even so.

     . And the latter consists in motion?

     . I told you so before.