e emotions and the power of the mind over them
which I pursued in our previous discussion of God and the mind, and I
shall consider human actions and appetites just as if I were considering
lines, planes or bodies.

_Definitions_

I.--I call that an adequate cause whose effect can be clearly and
distinctly perceived by means of the cause. I call that an inadequate or
partial cause whose effect cannot be understood by means of the cause
alone.

II.--I say that we act when anything is done, either within us or
without us, of which we are the adequate cause, that is to say (by the
preceding Definition), when from our nature anything follows, either
within us or without us, which by that nature alone can be clearly and
distinctly understood. On the other hand, I say that we suffer when
anything is done within us, or when anything follows from our nature, of
which we are not the cause excepting partially.

III.--By emotion I understand the modifications of the body, by which
the power of acting of the body itself is increased, diminished, helped,
or hindered, together with the ideas of these modifications.

If, therefore, we can be the adequate cause of any of these
modifications, I understand the emotion to be an action, otherwise it is
a passion.

_Postulates_

1.--The human body can be affected in many ways by which its power of
acting is increased or diminished, and also in other ways which make its
power of acting neither greater nor less.

2.--The human body is capable of suffering many changes, and,
nevertheless, can retain the impressions or traces of objects, and
consequently the same images of things.

_The Two States of Mind: Active and Passive_

In every human mind some ideas are adequate, and others mutilated and
confused. But the ideas which in any mind are adequate are adequate in
God in so far as He forms the essence of that mind, while those again
which are inadequate in the mind are also adequate in God, not in so far
as He contains the essence of that mind only, but in so far as He
contains the ideas of other things at the same time in Himself. Again,
from any given idea some effect must necessarily follow, of which God is
the adequate cause, not in so far as He is infinite, but in so far as He
is considered as affected with the given idea. But of that effect of
which God is the cause, in so far as He is affected by an idea which is
adequate in any mind, that same mind is the adequate ca