"[Brackets] enclose editorial explanations. Small ·dots· enclose material that has been added, but can be read as though it were part of the original text. Occasional •bullets, and also indenting of passages that are not quotations, are meant as aids to grasping the structure of a sentence or a thought. Every four-point ellipsis . . . . indicates the omission of a brief passage that seems to present more difficulty than it is worth. Longer omissions are reported between brackets."
From Passions of the Soul
17. The soul’s functions
* – thought: This translates Descartes’s pensée, but remember that he uses this word to cover mental events of all kinds, not merely ones that you and I would call ‘thoughtful’.
Now that we have looked at all the things the body can do unaided, it’s easy for us to see that there is nothing in us that we must attribute to our soul except our thoughts*. There are two main kinds of thoughts—actions of the soul and passions of the soul. The ones I call ‘actions’ are all our volitions, ·i.e. acts of the will·, because we experience them as coming directly from our soul with, apparently, no input from anything else. On the other hand, our various perceptions or items of knowledge can be called the soul’s ‘passions’—taking this word in a very general sense—because they are often not ·actively· made by our soul but rather ·passively· received by the soul from the things that they represent.
18. The will
† – will: When this occurs as a verb, it translates vouloir, which ordinarily means ‘want’. This version speaks of our ‘willing’ something in contexts where Descartes is clearly thinking of this as something we do, as an act of the will, a volition. You’ll get the idea if you try replacing ‘will’ by ‘want’ in articles 18 and 19.
Our volitions in their turn divide into two sorts: •actions of the soul that aim only at something in the soul itself, as when we will† to love God or in any way to apply our mind to some object that isn’t material; and •actions of the soul that aim at some event in our body, as when we will to walk. . . .
Our perceptions (·or items of knowledge·) are also of two sorts, one sort caused by the soul and the other sort by the body. The ones caused by the soul are our perceptions of our volitions and of all the •imaginings or other thoughts that depend on •them. We can’t will anything without thereby perceiving that we are willing it—that’s for sure. And although our soul is active in willing, it is passive in its perception of that action. But because this perception is really one and the same thing as the volition, and names are always based on whatever sounds better, we usually don’t call it a ‘passion’ but an ‘action’.
30. The soul is united to all the body’s parts together
For a perfect grasp of all this we need to recognize that the soul is really joined to the whole body, and can’t properly be said to exist in any one part of the body rather than in others. Why? •Because the body is a unity that is in a way indivisible—its organs are so arranged that the removal of any one of them makes the whole body defective. And •because the nature of the soul won’t let it have any relation to extension, or to the dimensions or other properties of the matter the body is made of; all it can be related to is the whole assemblage of the body’s organs. You can see this in the inconceivability of half a soul or a third of a soul, or of a soul’s size. And in the fact that the soul doesn’t shrink if we amputate some part of the body, and that if the assemblage of the body’s organs is broken up the soul completely separates from the body.
31. There’s a little gland in the brain where the soul does its work more particularly than elsewhere in the body
‡ – The French is plus particulièrement ; Descartes doesn’t explain this, and his uses of the adverb elsewhere, e.g. in articles 27 and 29, don’t help with this one. Judging by the next few pages we can take him to be saying that this gland is where the soul does most of its work or the most important part of it.
Although the soul is joined to the whole body, there’s a certain part of the body where it exercises its functions more particularly than in all the others.‡ It’s commonly thought that this part is •the brain, because of its relation to the sense-organs, or •the heart, because it feels to us as though that’s where our passions are. But on looking into this very carefully I think I can clearly see that the part of the body in which the soul directly [immédiatement ] does its work is. . . .a certain very small gland deep inside the brain, in a position such that. . . .the slightest movements by it can greatly alter the course of the nearby spirits passing through the brain, and conversely any little change in the course of those spirits can greatly alter the movements of the gland.
32. How we know that this gland is the principal seat of the soul
What convinces me that this gland is the only place in the body where the soul can directly exercise its functions is my conviction that all the other parts of our brain are double, as are all the organs of our external senses—eyes, hands, ears and so on. ·The fact that sense-organs come in pairs is central to my argument·. We often have one simple thought about one object at one time; so there must be some place where two sense-impressions coming through a matched pair of sense-organs can be brought together in a single impression before reaching the soul, so that they don’t present it with two objects instead of one. It makes sense to think of these impressions as being unified in this gland by means of the spirits that brush by it going into the brain. There’s nowhere else in the body where they could exist in the unified form except as a result of the unifying activities of this gland.
33. The seat of the passions is not in the heart
As for the view that the soul receives its passions in the heart: this is negligible because it is based solely on the fact that the passions make us feel some change in the heart; and it’s easy to see that the only reason for this feeling is that there’s a small nerve running down from the brain to the heart. In the same way, pain is felt as in the foot by means of the nerves in the foot, and the stars are perceived as in the sky by means of their light and the optic nerves. The soul doesn’t have to do its work in the heart in order to feel its passions there, any more than it has to be in the sky in order to see the stars there!
34. How the soul interacts with the body
Let us take it, then, that the soul’s principal seat is in the small gland located in the middle of the brain. From there it radiates out through the rest of the body by means of the animal spirits, the nerves, and even the blood, which can take on the impressions of the spirits and carry them through the arteries to all parts of the body. Remember what I said about our body’s machine:
The nerve-fibres are distributed through the body in such a way that when the objects of the senses stir up various movements in different parts of the body, the fibres open the brain’s pores in various ways; which brings it about that the animal spirits contained in those cavities enter the muscles in various ways. That is how the spirits can move the parts of the body in all the different ways they can be moved. . . .
To this we can now add:
The little gland that is the principal seat of the soul is suspended within the cavities containing these spirits, so that it can be moved by them in as many different ways as there are perceptible differences in the objects. But it can also be moved in various different ways by the soul, whose nature is such that it receives as many different impressions—i.e. has as many different perceptions—as there occur different movements in this gland. And, the other way around, the body’s machine is so constructed that just by this gland’s being moved in any way by the soul or by any other cause, it drives the surrounding spirits towards the pores of the brain, which direct them through the nerves to the muscles—which is how the gland makes them move the limbs [‘them’ could refer to the nerves or to the muscles; the French leaves that open].
35. Example of how the impressions of objects are united in the gland in the middle of the brain
If we see an animal approaching us, the light reflected from its body forms two images, one in each of our eyes; and these images form two others, by means of the optic nerves, on a surface in the brain facing in on its cavities. Then, by means of the spirits that fill these cavities, the images radiate towards the little gland that is surrounded by the spirits; the movement belonging to each point of one of the images tends towards the same point on the gland as the movement belonging to the corresponding point of the other image. . . . In this way, the two images in the brain create only one image on the gland, which acts directly on the soul and makes it see the shape of the animal.
36. Example of how passions are aroused in the soul
If this shape is very strange and terrifying—i.e. if it is closely related to things that have previously been harmful to the body—this arouses in the soul the passion of •anxiety, fol- lowed by that of •bold defiance or •fear and terror, depending on the state of the body or the strength of the soul, and on whether we have had past experience of coping with such things by fight or flight. In some people this ·frightening image· puts the brain into a state where the spirits reflected from the image formed on the gland proceed from there
(1) partly to the nerves that serve to turn the back and move the legs in order to flee, and partly
(2a) to the nerves that expand or constrict the openings to the heart, or else
(2b) to nerves that agitate other parts of the body from which blood is sent to the heart,
§ – Descartes famously had a problem explaining what could be going on in causal interactions between souls and bodies. In this paragraph he doesn’t speak of the soul’s acting on the body, and regarding the body’s acting on the soul he says only that a certain movement is institué de la nature pour faire sentir à l’âme cette passion—set up by nature to make the soul feel fear.
with (2) (whether a or b) happening in such a way that the blood is rarefied in an unusual way that makes it send to the brain spirits that are adapted for maintaining and strengthening the passion of fear —that is, for holding open or re-opening the pores of the brain that direct the spirits into these same nerves. For merely by entering into these pores they produce in the gland a particular movement that nature has set up so as to make the soul feel this passion. And because these pores are related mainly to the little nerves that serve to contract or expand the openings to the heart, this brings it about that the soul feels the passion chiefly as if it were in the heart.§
15. The causes of the differences among the spirits
¥ – Descartes adds two rather wordy details about how this can happen: •nerves that control the widths of openings to the heart; and •differences in the strength of thrust of spirits from different parts of the body.
This inequality can arise from differences in the materials of which the spirits are composed. We see this in people who have drunk a lot of wine: the wine’s vapours get quickly into the blood and rise from the heart to the brain, where they turn into spirits which, being stronger and more abundant than the spirits that are usually there, can move the body in many strange ways. Such differences among the spirits can also come from differences in the conditions of the heart, liver, stomach, spleen and all the other organs that help to produce them.¥
44. Each volition is naturally joined to a certain movement of the gland, but through effort or habit it can be joined to others ·as well·
What makes us produce some movement or other effect in ourselves isn’t always a volition to do just that, because nature or habit has established a variety of different links between thoughts and movements of the gland. (A) An example ·involving nature·: if we will to adjust our eyes to look at a far -distant object, this volition brings it about that the pupils grow larger; and if we will to adjust them to look at a very near object, this volition brings it about that the pupils contract. But if we want to get our pupil enlarged, it’s no use our willing to enlarge them —we won’t get them enlarged in that way! That is because nature has joined
•the movement of the gland by which spirits are driven to the optic nerve in the way needed for enlarging or contracting the pupils
•the volition to enlarge or contract the pupils
but rather to
•the volition to look at distant or nearby objects.
* – Of those two examples, only (B) illustrates the thesis announced in the heading of article 44. But they jointly illustrate the two parts of the first sentence of the article. In moving from the heading to the article Descartes seems to have drifted a little…
•the action of the soul (which, by means of the gland, can move the tongue and lips)
•those movements themselves
but rather with
•the meaning of the words that ensue from those movements.*
50. Any soul, however weak, can if well-directed acquire absolute power over its passions
As I have already said, although nature seems to have set up in us at birth specific links between gland-movements and thoughts, we can replace some of those links by others through habit. Experience shows this in the case of language. Words produce gland-movements that nature has ordained to represent to the soul only their sounds (spoken words) or shapes (written words); but because we have acquired the habit of thinking of their meanings when we hear or see them, that is what our thoughts go to—the meanings, not the sounds or shapes—when we see or hear those words. Another point: although the movements of the gland, the are naturally linked to ones that produce certain passions in it, it’s always possible through habit to break those links and associate those movements with very different passions instead; and indeed this habit can be acquired by a single event, with no need for long practice. For example: when we unexpectedly come upon something disgusting in food that we have been eating and enjoying, our surprise may re-organise our brain in such a way that we can’t afterwards look at any such food without revulsion, though until then we ate it with pleasure. The same thing can be seen in beasts: although they lack reason, and perhaps even lack thought, all the movements of the spirits and of the gland that produce passions in us are present in them too, though in them they maintain and strengthen only •the movements of the nerves and the muscles that usually accompany the passions and not, as in us, •the passions themselves. When a dog sees a partridge, it is naturally disposed to run towards it; and when it hears a gun fired, the noise naturally impels it to run away; but setters are commonly trained so that the sight of a partridge makes them stop, and the subsequent gun-shot makes them run towards the bird. It’s useful to know these things as encouragement to each of us to work on controlling our passions. For since we can with a little effort change the movements of the brain in animals devoid of reason, it is evident that we can make an even better job of this in the case of men. Even those who have the weakest souls could acquire absolute mastery over all their passions if they worked hard enough at training and guiding them.