But though in this view of things we cannot refuse to condemn the materialists, who conjoin all thought with extension; yet a little reflection will show us equal reason for blaming their antagonists, who conjoin all thought with a simple and indivisible substance.  The most vulgar philosophy informs us, that no external object can make itself known to the mind immediately, and without the interposition of an image or perception.  That table, which just now appears to me, is only a perception, and all its qualities are qualities of a perception.  Now the most obvious of all its qualities is extension.  The perception consists of parts.  These parts are so situated, as to afford us the notion of distance and contiguity; of length, breadth, and thickness.  The termination of these three dimensions is what we call figure.  This figure is moveable, separable, and divisible.  Mobility, and separability are the distinguishing properties of extended objects.  And to cut short all disputes, the very idea of extension is copyed from nothing but an impression, and consequently must perfectly agree to it.  To say the idea of extension agrees to any thing, is to say it is extended.

The free-thinker may now triumph in his turn; and having found there are impressions and ideas really extended, may ask his antagonists, how they can incorporate a simple and indivisible subject with an extended perception?  All the arguments of Theologians may here be retorted upon them.  Is the indivisible subject, or immaterial substance, if you will, on the left or on the right hand of the perception?  Is it in this particular part, or in that other?  Is it in every part without being extended?  Or is it entire in any one part without deserting the rest?  It is impossible to give any answer to these questions, but what will both be absurd in itself, and will account for the union of our indivisible perceptions with an extended substance.

This gives me an occasion to take a-new into consideration the question concerning the substance of the soul; and though I have condemned that question as utterly unintelligible, yet I cannot forbear proposing some farther reflections concerning it.  I assert, that the doctrine of the immateriality, simplicity, and indivisibility of a thinking substance is a true atheism, and will serve to justify all those sentiments, for which Spinoza is so universally infamous.  From this topic, I hope at least to reap one advantage, that my adversaries will not have any pretext to render the present doctrine odious by their declamations, when they see that they can be so easily retorted on them.