ons, from which the subject is of itself exempted.
These philosophers are the curious reasoners concerning the material or
immaterial substances, in which they suppose our perceptions to inhere.
In order to put a stop to these endless cavils on both sides, I know no
better method, than to ask these philosophers in a few words, What
they mean by substance and inhesion? And after they have answered
this question, it will then be reasonable, and not till then, to enter
seriously into the dispute.

This question we have found impossible to be answered with regard to
matter and body: But besides that in the case of the mind, it labours
under all the same difficulties, it is burthened with some additional
ones, which are peculiar to that subject. As every idea is derived from
a precedent impression, had we any idea of the substance of our minds,
we must also have an impression of it; which is very difficult, if
not impossible, to be conceived. For how can an impression represent a
substance, otherwise than by resembling it? And how can an impression
resemble a substance, since, according to this philosophy, it is not a
substance, and has none of the peculiar qualities or characteristics of
a substance?

But leaving the question of what may or may not be, for that other what
actually is, I desire those philosophers, who pretend that we have an
idea of the substance of our minds, to point out the impression that
produces it, and tell distinctly after what manner that impression
operates, and from what object it is derived. Is it an impression of
sensation or of reflection? Is it pleasant, or painful, or indifferent?
I Does it attend us at all times, or does it only return at intervals?
If at intervals, at what times principally does it return, and by what
causes is it produced?

If instead of answering these questions, any one should evade the
difficulty, by saying, that the definition of a substance is something
which may exist by itself; and that this definition ought to satisfy us:
should this be said, I should observe, that this definition agrees to
every thing, that can possibly be conceived; and never will serve to
distinguish substance from accident, or the soul from its perceptions.
For thus I reason. Whatever is clearly conceived may exist; and whatever
is clearly conceived, after any manner, may exist after the same manner.
This is one principle, which has been already acknowledged. Again, every
thing, which is dif