by to perceive them. I answer, you may so, there is no difficulty in it;
but what is all this, I beseech you, more than framing in your mind
certain ideas which you call BOOKS and TREES, and the same time omitting
to frame the idea of any one that may perceive them? BUT DO NOT YOU
YOURSELF PERCEIVE OR THINK OF THEM ALL THE WHILE? This therefore is
nothing to the purpose; it only shows you have the power of imagining or
forming ideas in your mind: but it does not show that you can conceive it
possible the objects of your thought may exist without the mind. To make
out this, IT IS NECESSARY THAT YOU CONCEIVE THEM EXISTING UNCONCEIVED OR
UNTHOUGHT OF, WHICH IS A MANIFEST REPUGNANCY. When we do our utmost to
conceive the existence of external bodies, we are all the while only
contemplating our own ideas. But the mind taking no notice of itself, is
deluded to think it can and does conceive bodies existing unthought of or
without the mind, though at the same time they are apprehended by or
exist in itself. A little attention will discover to any one the truth
and evidence of what is here said, and make it unnecessary to insist on
any other proofs against the existence of material substance.

24. THE ABSOLUTE EXISTENCE OF UNTHINKING THINGS ARE WORDS WITHOUT
A MEANING.--It is very obvious, upon the least inquiry into our thoughts,
to know whether it is possible for us to understand what is meant by the
ABSOLUTE EXISTENCE OF SENSIBLE OBJECTS IN THEMSELVES, OR WITHOUT THE MIND.
To me it is evident those words mark out either a direct contradiction, or
else nothing at all. And to convince others of this, I know no readier or
fairer way than to entreat they would calmly attend to their own
thoughts; and if by this attention the emptiness or repugnancy of those
expressions does appear, surely nothing more is requisite for the
conviction. It is on this therefore that I insist, to wit, that the
ABSOLUTE existence of unthinking things are words without a meaning, or
which include a contradiction. This is what I repeat and inculcate, and