What are the Passions of the Soul?

1. What is Passion in relation to one subject is always Action in another respect.

The deficiency of the sciences that we have inherited from the ancients is most obvious with what they have written about the Passions.

Everyone experiences the passions within themselves. This makes the knowledge about it always highly sought after.

But what the ancients have taught us is so little and mostly so hard to believe. This is why I must approach the truth by deviating from the paths they followed.

Therefore, I will be obliged to write here as if treating a subject that no one before me had ever touched upon.

To begin, I consider that everything that happens, or occurs anew, is generally called by philosophers a Passion with regard to the subject to which it happens and an Action with regard to the one who causes it to happen.

So that although the agent and the patient are often very different, Action and Passion remain always the same thing, which has these two names by reason of the two different subjects to which it can be related.

2. To know the Passions of the soul, we must distinguish its functions from those of the body

I also consider that we do not notice any subject acting more immediately against our soul than the body to which it is joined.

Consequently, we must think that what is a Passion in the soul is commonly an Action in the body.

Therefore, there is no better way to understand our Passions than by examining the difference between the soul and the body to know to which of the two we should attribute each of the functions that are in us.

3. What rule should be followed for this purpose

Everything we experience in ourselves, and that we see can also exist in completely inanimate bodies, must be attributed only to our body.

Conversely, that everything in us which we cannot in any way conceive as belonging to a body must be attributed to our soul.

4. That heat and movement of the limbs proceed from the body, and thoughts from the soul

All types of thoughts in us belong to the soul.

A flame alone has much more heat and movement than any of our limbs.

There are inanimate bodies that:

• can move in as many or more diverse ways than ours,
• have as much or more heat than our bodies

All the heat and all the movements in us, insofar as they do not depend on thought, belong only to the body.

5. The soul does not give movement and heat to the body

People have imagined that it the absence of the soul in dead bodies causes the movements and the heat of the body to cease. This is because they have unreasonably believed that our natural heat and all the movements of our bodies depend on the soul.

This wrong idea is why there has been no good explanation of the Passions up to now.

Instead, they should have thought the opposite, that the soul only departs when one dies because this heat ceases and the organs that serve to move the body become corrupted.

6. What is the difference between a living body and a dead body

Death never occurs due to the fault of the soul, but only because some of the principal parts of the body become corrupted.

The body of a living man differs as much from that of a dead man as a working clock is different from a broken one that ceases to act.

7. The Parts of the Body, and Some of Their Functions

The food we eat goes down into the stomach and intestines, from where their juice flows into the liver and all the veins, mixing with the blood they contain, and thus increasing its quantity.

All the blood from the veins can easily flow from the vena cava into its right side.

From there, it passes into the lungs through the pulmonary artery. It then returns from the lungs into the left side of the heart through the the pulmonary vein.

Finally, it pass from there into the aorta, whose branches spread throughout the body.

Even those who have not been completely blinded by the authority of the Ancients and who have opened their eyes to examine Harvey’s opinion on the circulation of the blood do not doubt that all

The veins and arteries of the body are like streams through which the blood flows continuously very quickly.

It starts from the right cavity of the heart through the pulmonary artery, whose branches are scattered throughout the lungs and joined to those of the pulmonary vein, through which it passes from the lungs into the left side of the heart.

From there, it goes into the aorta, whose branches spread throughout the rest of the body are joined to the branches of the vena cava, which again carry the same blood into the right cavity of the heart.

These two cavities are like locks, through each of which all the blood passes with each turn it makes in the body.

All the movements of the limbs depend on the muscles.

These muscles are opposed to each other in such a way that when one of them shortens, it pulls towards itself the part of the body to which it is attached, which simultaneously lengthens the muscle that is opposed to it:

Then if it happens at another time that this latter shortens, it makes the former lengthen, and it pulls towards itself the part to which they are attached.

These muscle movements, as well as all the senses, depend on the nerves, which are like little threads or small tubes that all come from the brain and contain, as does the brain, a certain very subtle air or wind, called the animal spirits.

8. What is the Principle of All These Functions

But it is not commonly known how these animal spirits and these nerves contribute to movements and senses, nor what is the corporeal Principle that makes them act.

While we are alive, there is a continuous heat in our heart. It is a kind of fire that the blood from the veins maintains there. This fire is the corporeal principle of all the movements of our limbs.

9. How the Heart Moves

Its first effect is that it dilates the blood with which the cavities of the heart are filled.

This causes the blood, needing to occupy a larger space, to rush with force from the right cavity into the pulmonary artery, and from the left into the aorta.

Then this dilation ceasing, new blood immediately enters from the vena cava into the right cavity of the heart, and from the pulmonary vein into the left.

For there are small flaps at the entrances of these four vessels so arranged that they ensure the blood can only enter the heart through the last two, and exit only through the first two.

The new blood that enters the heart is immediately rarefied in the same way as the previous one. And it is in this alone that the pulse or beating of the heart and arteries consists; so that this beating is repeated as many times as new blood enters the heart.

This alone also gives the blood its movement and makes it flow very quickly through all the arteries and veins; by which means it carries the heat it acquires in the heart to all other parts of the body; and it serves them as nourishment.