mind is fitted to
perceive adequately more things, in proportion as its body has
more in common with other bodies.

PROP. XL. Whatsoever ideas in the mind follow from ideas which
are therein adequate, are also themselves adequate.

Proof.--This proposition is self--evident. For when we say
that an idea in the human mind follows from ideas which are
therein adequate, we say, in other words (II. xi. Coroll.), that
an idea is in the divine intellect, whereof God is the cause, not
in so far as he is infinite, nor in so far as he is affected by
the ideas of very many particular things, but only in so far as
he constitutes the essence of the human mind.

Note I.--I have thus set forth the cause of those notions,
which are common to all men, and which form the basis of our
ratiocination. But there are other causes of certain axioms or
notions, which it would be to the purpose to set forth by this
method of ours; for it would thus appear what notions are more
useful than others, and what notions have scarcely any use at
all. Furthermore, we should see what notions are common to all
men, and what notions are only clear and distinct to those who
are unshackled by prejudice, and we should detect those which are
ill--founded. Again we should discern whence the notions called
secondary derived their origin, and consequently the axioms on
which they are founded, and other points of interest connected
with these questions. But I have decided to pass over the
subject here, partly because I have set it aside for another
treatise, partly because I am afraid of wearying the reader by
too great prolixity. Nevertheless, in order not to omit anything
necessary to be known, I will briefly set down the causes, whence
are derived the terms styled transcendental, such as Being,
Thing, Something. These terms arose from the fact, that the
human body, being limited, is only capable of distinctly forming
a certain number of images (what an image is I explained in the
II. xvii. note) within itself at the same time; if this number
be exceeded, the images will begin to be confused; if this
number of images, of which the body is capable of forming
distinctly within itself, be largely exceeded, all will become
entirely confused one with another. This being so, it is evident
(from II. Prop. xvii. Coroll., and xviii.) that the human mind
can distinctly imagine as many things simultaneously, as its body
can form images simultaneously. When t