HYL.  I acknowledge I know not how.

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

HYL.  They are.

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

HYL.  I cannot.

Phil.  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?

HYL.  By no means.

Phil.  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?

HYL.  I think so.

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

HYL.  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.

Phil.  What reason is there for that, Hylas?

HYL.  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.

Phil.  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.

HYL.  It is this very motion in the external air that produces in the mind the sensation of sound.  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 sound.

Phil.  What! is sound then a sensation?

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

Phil.  And can any sensation exist without the mind?

HYL.  No, certainly.

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

HYL.  You must distinguish, Philonous, between sound as it is 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.

Phil.  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?