substances: the latter are inert, fleeting, dependent beings, which
subsist not by themselves, but are supported by, or exist in minds or
spiritual substances. We comprehend our own existence by inward feeling
or reflexion, and that of other spirits by reason. We may be said to have
some knowledge or notion of our own minds, of spirits and active beings,
whereof in a strict sense we have not ideas. In like manner, we know and
have a notion of relations between things or ideas--which relations are
distinct from the ideas or things related, inasmuch as the latter may be
perceived by us without our perceiving the former. To me it seems that
ideas, spirits, and relations are all in their respective kinds the
object of human knowledge and subject of discourse; and that the term
idea would be improperly extended to signify everything we know or have
any notion of.

90. EXTERNAL THINGS EITHER IMPRINTED BY OR PERCEIVED BY SOME OTHER MIND.--
Ideas imprinted on the senses are real things, or do really exist;
this we do not deny, but we deny they can subsist without the minds which
perceive them, or that they are resemblances of any archetypes existing
without the mind; since the very being of a sensation or idea consists in
being perceived, and an idea can be like nothing but an idea. Again, the
things perceived by sense may be termed external, with regard to their
origin--in that they are not generated from within by the mind itself,
but imprinted by a Spirit distinct from that which perceives them.
Sensible objects may likewise be said to be "without the mind" in another
sense, namely when they exist in some other mind; thus, when I shut my
eyes, the things I saw may still exist, but it must be in another mind.

91. SENSIBLE QUALITIES REAL.--It were a mistake to think that what
is here said derogates in the least from the reality of things.
It is acknowledged, on the received principles, that extension,