Phil.  Pray what is it that distinguishes one motion, or one part of extension, from another?  Is it not something sensible, as some degree of swiftness or slowness, some certain magnitude or figure peculiar to each?

HYL.  I think so.

Phil.  These qualities, therefore, stripped of all sensible properties, are without all specific and numerical differences, as the schools call them.

HYL.  They are.

Phil.  That is to say, they are extension in general, and motion in general.

HYL.  Let it be so.

Phil.  But it is a universally received maxim that everything which exists is particular.  How then can motion in general, or extension in general, exist in any corporeal substance?

HYL.  I will take time to solve your difficulty.

Phil.  But I think the point may be speedily decided.  Without doubt you can tell whether you are able to frame this or that idea.  Now I am content to put our dispute on this issue.  If you can frame in your thoughts a distinct abstract idea of motion or extension, divested of all those sensible modes, as swift and slow, great and small, round and square, and the like, which are acknowledged to exist only in the mind, I will then yield the point you contend for.  But if you cannot, it will be unreasonable on your side to insist any longer upon what you have no notion of.

HYL.  To confess ingenuously, I cannot.

Phil.  Can you even separate the ideas of extension and motion from the ideas of all those qualities which they who make the distinction term secondary?

HYL.  What! is it not an easy matter to consider extension and motion by themselves, abstracted from all other sensible qualities?  Pray how do the mathematicians treat of them?

Phil.  I acknowledge, Hylas, it is not difficult to form general propositions and reasonings about those qualities, without mentioning any other; and, in this sense, to consider or treat of them abstractedly.  But, how doth it follow that, because I can pronounce the word motion by itself, I can form the idea of it in my mind exclusive of body? or, because theorems may be made of extension and figures, without any mention of great or small, or any other sensible mode or quality, that therefore it is possible such an abstract idea of extension, without any particular size or figure, or sensible quality, should be distinctly formed, and apprehended by the mind?  Mathematicians treat of quantity, without regarding what other sensible. qualities it is attended with, as being altogether indifferent to their demonstrations.  But, when laying aside the words, they contemplate the bare ideas, I believe you will find, they are not the pure abstracted ideas of extension.

HYL.  But what say you to pure intellect?  May not abstracted ideas be framed by that faculty?