Benedict de Spinoza, THE ETHICS
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external body and in the whole, there will be an adequate idea of
A in God (II. vii. Cor.), both in so far as he has the idea of
the human body, and in so far as he has the ideas of the given
external bodies. Let it now be granted, that the human body is
affected by an external body through that, which it has in common
therewith, namely, A; the idea of this modification will involve
the property A (II. xvi.), and therefore (II. vii. Cor.) the
idea of this modification, in so far as it involves the property
A, will be adequate in God, in so far as God is affected by the
idea of the human body; that is (II. xiii.), in so far as he
constitutes the nature of the human mind; therefore (II. xi.
Cor.) this idea is also adequate in the human mind. Q.E.D.

<<<<perceive adequately more things, in proportion as its body has
more in common with other bodies.

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. Cor.), 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
ratiocinations. 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