Spinoza
Ethics
FIFTH PART Concerning the power of the intellect or, on human freedom
de modo sive via quae ad libertatem ducit mentis libertas seu beatitudo
The stoics were of opinion that the emotions depend absolutely on our free will, and that we have absolute command them.
Descartes held that the soul or mind was particularly united to a certain part of the brain, called the pineal gland, by means of which the mind senses all the movements that take place in the body and external objects, and which the mind by the very fact that it wills can move in various ways. He held that this gland is suspended in the middle of the brain in such a way that it can be moved by the least motion of the animal spirit.
... although the mind had firmly proposed to go out against dangers and had joined to this decision the motion of daring, yet at the sight of the peril the gland would be so suspended that the mind would only be able to think of flight.
Therefore, inasmuch as the mind's power, is defined by understanding alone, the remedies for the emotions we shall determine from mere knowledge of the mind and deduce there from all things which relate to its blessedness.
AXIOMS
I. If in the same subject two contrary actions are excited, a change must take place in both or in one of them until they cease to be contrary.
PROP. III. An emotion which is a passion ceases to be a passion as soon as we form a clear and distinct idea of it.
Corollary. Therefore the more an emotion becomes known to us, the more it is within our power and the less our mind is passive in regard to it.
PROP. V. Emotion towards a thing which we imagine simply and not as necessary nor possible nor contingent, is, caeteris paribus, the greatest of all.
Proof. Emotions towards a thing which we imagine to be free is greater that that towards one which is necessary, and consequently still greater than that towards a thing which we imagine as possible or contingent. But to imagine a thing as free can be nothing else than to imagine it simply while we are ignorant of the causes by which it was determined for acting. Therefore emotions towards a thing which we imagine simply is greater, caeteris paribus, than towards a thing necessary, possible, or contingent, and consequently the greatest.
