Proposition I: The mind is active insofar as it has adequate ideas and passive insofar as it has ina… — Baruch Spinoza

Proposition I: The mind is active insofar as it has adequate ideas and passive insofar as it has inadequate ideas; susceptibility to being acted upon varies with the proportion of inadequate ideas.

By Baruch Spinoza, from Ethics

Key Arguments

In every human mind there are both adequate and inadequate ideas; adequate ideas in the mind are adequate in God insofar as he constitutes that mind, whereas inadequate ideas in the mind are adequate in God only insofar as he contains other minds.
From any idea some effect necessarily follows; of the effect caused by God as affected by an idea adequate in a given mind, that mind is the adequate cause and thus active.
When an effect follows from God as containing the minds of other things also, the given human mind is only a partial cause and thus passive.
Corollary explicitly links more passivity to more inadequate ideas and more activity to more adequate ideas.

Source Quotes

I. Our mind is in certain cases active, and in certain cases passive. In so far as it has adequate ideas it is necessarily active, and in so far as it has inadequate ideas, it is necessarily passive. Proof.—In every human mind there are some adequate ideas, and some ideas that are fragmentary and confused (II. xl. note).

Coroll.), and those which are inadequate in the mind are likewise (by the same Coroll.) adequate in God, not inasmuch as he contains in himself the essence of the given mind alone, but as he, at the same time, contains the minds of other things. Again, from any given idea some effect must necessarily follow (I. 36); of this effect God is the adequate cause (III.

Def. i.), not inasmuch as he is infinite, but inasmuch as he is conceived as affected by the given idea (II. ix.). But of that effect whereof God is the cause, inasmuch as he is affected by an idea which is adequate in a given mind, of that effect, I repeat, the mind in question is the adequate cause (II. xi. Coroll.).

Coroll.) the mind of the given man is not an adequate, but only a partial cause; thus (III. Def. ii.) the mind, inasmuch as it has inadequate ideas, is in certain cases necessarily passive; this was our second point. Therefore our mind, &c.

Therefore our mind, &c. Q.E.D. Corollary.—Hence it follows that the mind is more or less liable to be acted upon, in proportion as it possesses inadequate ideas, and, contrariwise, is more or less active in proportion as it possesses adequate ideas. PROP.

Key Concepts

Our mind is in certain cases active, and in certain cases passive. In so far as it has adequate ideas it is necessarily active, and in so far as it has inadequate ideas, it is necessarily passive.
from any given idea some effect must necessarily follow
of that effect, I repeat, the mind in question is the adequate cause
the mind, inasmuch as it has inadequate ideas, is in certain cases necessarily passive
the mind is more or less liable to be acted upon, in proportion as it possesses inadequate ideas, and, contrariwise, is more or less active in proportion as it possesses adequate ideas.

Context

Ethics, Part III, PROP. I with Proof and Corollary (lines 1749–1876); foundational agency criterion for affects