I mean, I repeat, the faculty, whereby the mind affirms or denies what is true or false, not the desire, wherewith the mind wishes for or turns away from any given thing.
After we have proved, that these faculties of ours are general notions, which cannot be distinguished from the particular instances on which they are based, we must inquire whether volitions themselves are anything besides the ideas of things.
We must inquire, I say, whether there is in the mind any affirmation or negation beyond that, which the idea, in so far as it is an idea, involves.

On which subject see the following proposition, and II.Def.iii., lest the idea of pictures should suggest itself.

For by ideas I do not mean images such as are formed at the back of the eye, or in the midst of the brain, but the conceptions of thought.
PROP.XLIX.

There is in the mind no volition or affirmation and negation, save that which an idea, inasmuch as it is an idea, involves.
Proof .-- There is in the mind no absolute faculty of positive or negative volition, but only particular volitions, namely, this or that affirmation, and this or that negation.

Now let us conceive a particular volition, namely, the mode of thinking whereby the mind affirms, that the three interior angles of a triangle are equal to two right angles.