Part Five

Origin of Non-Pure Ideas, which derive Something from Feeling

630. So far we have spoken about ideas that come from deep within being and are obtained either through analysis of this form-idea or by considering its relationships; no determination of it by feeling has been suggested to our mind. We have called them pure ideas because they involve only being in all its universality, the simplest of all principles.

We must now gradually apply this pure part of our knowledge to feelings, to explain the origin of non-pure ideas. Non-pure ideas proceed not only from the formal principle but also from a principle of spiritual and animal feeling associated with it in our subjective unity.

631. We will first deal with the pure idea of substance and then see how feeling makes it a specific idea, changing it into the idea of the substance of spirit by means of the spiritual feeling, and into the idea of the substance of matter and body by means of the material, corporeal feeling.

CHAPTER 1.

Origin of the difference between the ideas of corporeal substance

and spiritual substance

632. We have shown how, on the occasion of external and internal sensations, the understanding naturally conceives the ideas of substance and cause. This refuted Hume's system which affirmed that in the whole universe nothing existed except pure ideas, pure accidents, pure facts, without subject or cause.
Hume, applying all the force of his genius to creating a totally empty doctrine, an idol in which he can worship himself, bequeaths to the world one of the best known sophisms.

His genius and his profound, zealous meditations produced a monster, 'a wonder for every well-grounded heart'. Standing at the height of a culture proudly proclaimed by the century, he reveals his ignorance of what is known even to the most humble, uneducated person, and clearly understood by the most uncivilised of people. Ideas, which to the minds of others are extremely simple, elementary and clear, go awry in the mind of Hume; they become blurred and lose all the light which enables them, like most faithful stars, to shine before the human family. Dazzled and blind to these ideas, Hume gropes about for them; unable to find them, he imagines and falsifies them, recreating them without any exemplar. In the end, even someone who had lost all common sense would be a better judge of the matter.

633. From what has been said, we can conclude:

1. Hume does not know what substance and cause are, nor what accident and effect are. Although he speaks about these things, he makes no attempt to investigate what the world understands by 'accidents', 'substance', 'causes' and 'effects'. He gives the words an arbitrary meaning. For him they are contemptible -woe to anything that is contemptible for a philosopher! But he is in fact attacking his own creations, not ideas expressed by words.

2. He groups into one idea the three distinct ideas of sensible quality, sensation and intellective conception.

3. With this one idea (a monster with three heads) he has limited the number of things that make up the universe: he has made one species out of three.

4. Nevertheless, sensible qualities, sensations and ideas, reduced to a single thing (a pure idea), left two elements in the universe: ideas and their subject. So, because the world still lacked sufficient philosophical regularity, Hume ingeniously decreed that the world was one, single thing, and that subject and idea were identical, that is, he destroyed the subject, leaving only pure idea. Thus, the universe, through Hume's decree, was reduced to perfect simplicity; there was no longer anything decorative in it. At last, human artistry had remedied the imperfections of the Creator!

634. Now, I have shown how absurd it is to grant the existence of sensible qualities without a substance or act through which they exist. I have also shown that our concept of the universe is neither of accidents alone nor of substances alone but of accidents and substances. However I have not investigated the nature of the substance through which sensible qualities exist; I have not answered Berkeley who maintains that the subject of sensible qualities is not something different from us, but ourselves. According to him, the substance of our spirit is the sole subject of sensible qualities and of our internal feelings. It is also certain that common sense censures this system and that the idea people form of the subject of corporeal, sensible qualities is different from the idea of the subject of their internal feelings. This is a fact to be explained; we must therefore examine the origin of the difference between the idea of corporeal substance and the idea of spiritual substance.

635. Berkeley, unlike Hume, does not deny a subject to sensible qualities. He simply says that we ourselves are the subject and that there is nothing outside us. Common sense accepts, with Berkeley, that we are subject to sensations but adds that sensations come from an external cause in which there must be different energies corresponding to and producing the different kinds of sensations we experience. We can call these energies sensible qualities. Common sense also affirms that this cause is a substance and the necessary subject of these qualities or powers. Berkeley's idealism distinguishes only two things in the fact of sensations: 1. sensations and 2. their subject (myself), nothing more. The realism of common sense distinguishes four things in the same fact: 1. sensations; 2. their subject (ourselves); 3. the sensible qualities, what is felt; and 4. the subject of the sensible qualities, body: two subjects with their qualities instead of one. We must see which of the two systems is more true to nature. Does Berkeley's idealism omit real facts, which should be noted or, in the system of common sense, does popular imagination introduce non-existent facts?

636. Before I begin this investigation however, I will clarify further the notions of subject and cause. Only a proper understanding of these notions will enable us to see things clearly and find firm ground as we discuss such obscure matters.

637. One thing that produces another is its cause but not always its subject. The thing produced can have its own existence, that is, an existence seen mentally by us as separate from what produces it. It can also be without an existence of its own so that we can conceive it only as united with the same existence as the cause. In the first case, that which produces is only cause of the thing produced; in the second, it is both cause and subject. Granted that a son is an ens with his own separate existence, a father is only the cause of his son.(92) But the intelligent spirit is not only the cause of our thoughts, it is also their subject; our thoughts have the same existence as the spirit and can be conceived only as existing in our spirit that produces and holds them in being. In this case the spirit is at the same time subject.

When a cause therefore produces something remaining within it, it is said to be also subject of the thing produced. This is the case with our thoughts; they all remain within the spirit, of which they are inseparable modifications. On the other hand, a cause can act externally by detaching from itself the thing produced, which then acquires its own existence. That thing is now conceived in itself without need of the cause which, in this case, is only the cause not the subject of the thing produced.

638. This difference is true and important. Only one observation needs to be made: we must not misunderstand the statement 'When the thing produced remains within the cause, the cause is also subject.'
The word 'thing' in this proposition can give rise to misunderstanding.
It is generally used to mean that which exists in itself, while what is produced in a thing is a modification or something similar, of a thing, not a thing itself. So we must note that in our proposition the word 'thing' has a very wide meaning; it indicates everything we think in any mental conception, whether such an object has its own existence or not.

If what has been produced has no existence of its own, its conception is a pure abstraction which we could not arrive at without first thinking of that which produces it (subject). We do this later through abstraction by which we break down our first concept. We separate the accident from the subject and give it a name as if it were a thing per se, thus making it finally a mental object of our exclusive attention (a dialectic ens).

639. Having distinguished subject from cause we must now approach step by step the truth we are investigating.
To do this accurately, we will first limit ourselves to proving that in both subjects (spirit and body), about which common sense and the philosophy of Berkeley disagree, we can and must distinguish by mental abstraction a third thing between sensations with their sensible qualities and the pure act by which they exist. It is in fact impossible and contradictory to imagine that the act by which sensations or sensible qualities exist, extends to them only, irrespective of their union with anything else. This implies demonstrating that the subject we have proved to be joined to sensations and sensible qualities (whether there is one spirit, as Berkeley holds, or two, that is, there is also a body, subject of sensible qualities, in addition to the spirit, subject of sensations) cannot be simply and solely the act by which we understand sensations and sensible qualities to exist. Such an act presupposes an entity that, in addition to supporting sensations and sensible qualities, is also something in itself, that is, has an absolute property unrelated to things outside it.
I shall first speak about the subject of sensations, granted by both systems, and then about the subject 'body', granted only by realists and denied by Berkeley's idealist disciples.

640. I have distinguished sensations from that through which they exist, that is, their substance; I will now analyse this idea of substance.
When I analyse the energy by which sensations exist, its concept includes something more than the act of their existence. Careful consideration of the supposition about which the whole argument turns, shows the truth of my affirmation. We have supposed that we are ignorant of the existence of substance; all we know is that sensations exist. Given only this fact, I have demonstrated by analysis that the idea of a substance is contained necessarily and implicitly in this fact.

The second step of the argument is this: if we proceed to analyse substance found in this way, we encounter in its concept something more than an energy capable of making sensations subsist. The proof is as follows.
Sensations exist; therefore there is an energy making them exist. But what are these sensations, of colour, sound, taste, smell, etc. and how do they come about? Observation first shows that sensations happen in me (attention confirms this): colours, sounds, etc. are so much my own sensations that if I did not exist or could not feel, I would not only be deprived of them - they would not even exist. I am speaking about all the sensations I experience, which are quite different from those experienced by someone else. The sensations that I have when smelling an onion, listening to a violin or tasting an orange would not exist at all if I did not feel them. But what I say about my own sensations can be said equally about anyone's sensations: if they are sensations like those from which I draw the concept and understand the word 'sensations', then certainly they would not exist if there were no one to experience them or the person were deprived of feeling or were not actually experiencing them at the present moment. There is no sensation, colour, taste, etc. that is not found in human beings, since every colour, odour, taste etc. is a modification of the feeling of a sensitive ens.

Once this nature of sensations has been observed, it is clear that, in addition to sensations and the act of their existence, the sentient subject must contain something which is the foundation of their act of existence. This is so evident that it hardly needs proof.
When I say 'I smell odours, I see colours, etc.', I posit myself as the subject of the sensations perceived. Myself, however, is not simply the act by which they exist, because I do not find myself in the pure idea of existing sensation. On the contrary, without myself, I would have to think of as many things existing per se as there are sensations. But as I think of the existence of the sensations in the way I experience them, I am convinced that many of them are referred equally to just one myself. Hence myself that experiences many sensations is one, while the sensations are many; myself is different from the sensations just as the subject is different from the modifications it undergoes.

641. Furthermore, myself can experience many present sensations, which then give way to others. While this is happening, myself, despite the different sensations, remains itself. Thus it has the power to feel and to be modified, although the power to feel many sensations is totally different from each actual sensation.

642. Finally, sensations are felt by myself, while myself is that which feels. These two characteristics are not only different but opposite and as such clearly demonstrate that sensations and their act of existence cannot be conceived without the presence of a subject, that is, without their act of existence first terminating in something other than themselves, something from which they receive and have existence.

643. It must be noted in everything said so far that the sentient subject is not deduced by reasoning but by simple analysis of the idea, 'existing sensation'. Earlier I showed, against Hume, that to conceive an 'existing sensation' (Hume grants sensation) means to conceive a substance, and that we do this by analysing the idea of existing sensation. In the same way, I show here that to conceive a substance is to conceive something that exists different from sensations (their subject): this is the result of our analysis of the idea of substance.

644. A similar argument is used in the system of the realists to prove that it is impossible to think sensible qualities existing through an act that terminates in them alone. The act enabling these qualities to exist has to make something else exist, different from them.
In fact, for realists, sensible qualities are powers producing sensations in a sentient subject (cf. 635).
But it is absurd to imagine that these powers exist and that nothing exists which can be mentally distinguished from them.
Let us analyse the idea of existing sensible qualities, that is, of powers that excite sensations in us.

As realists understand them, all sensible qualities emanate from a sort of centre called 'body', assumed to be their subject. If these qualities are united in this way and refer to an ens from which they originate, this ens which potentially unites them, whatever it may be, must be implicit in their idea. In this case, in addition to qualities, this idea includes the existence of some other thing necessary for the existence of the qualities in the way we think of them.

645. It may be argued that this approach is not founded on the pure concept of sensible qualities but on the concept obtained from experience, and that the centre, the connection uniting these powers, has nothing to do with the pure concept. But if we examine just one sensible quality, we are still thinking of something in addition to the quality.
I define a sensible quality as a power which can produce a certain kind of sensation.

If this power really exists, we must think, and do in fact think of it as something in itself, other than in its relationship with us. This subsistence of the quality in itself is different from its relationship with us or its action on us because it is impossible to think of a pure relationship or action of an ens without thinking of the ens itself. It is impossible to have relationship and action between two entia, unless there are two entia. If, therefore, in conceiving a potency to modify me, I conceive the real relationship of something with me, we must say that something exists capable of modifying me. This potency is: 1. something existing independently of me; 2. a relationship and action that this something exhibits in me.
Thus the analysis of the concept 'existing sensible qualities or potency to produce sensations in me' results in two ideas: 1. the idea of an ens really existing in itself; and 2. the idea of a relationship with us or of an action producing sensations.
However, before continuing the demonstration of the existence of these two subjects, one spiritual, the other corporeal, we must say something about essence.

646. I define essence as that which is understood in any idea. An idea is the thing thought by me as simply possible. But this possible thing, considered in itself and independently of the mind that thinks it, is the essence. Essence therefore is everything I think in any idea whatsoever.

647. Determinate ideas are of two kinds, specific and generic. To these correspond two kinds of essences in our minds: specific essence, that is, what I think in the specific idea of a thing, and generic essence, that is, what I think in the generic idea.
Besides these two classes of more or less determinate ideas, there is idea in all its universality, the idea of being; what I think in the idea of being can be called most universal essence or simply essence (essentia from esse), as Plato often calls it.

648. I have already indicated that a thing can be considered in a perfect and complete state, or in more or less imperfect states. Imperfection is only a lack or privation; everybody accepts the truth that evil is simply the lack of good.
So the only idea we can have of something complete, free from every defect and imperfection, is the fully positive one. All the other ideas of inferior states are simply the first idea, the real type and exemplar of something, from which some perfection has been removed; they are modes of the idea (cf. 500-503 [500-509]). Specific essence, properly speaking, is what is thought in the complete, perfect idea; to this idea are reduced all other ideas of the thing in its various states of imperfection.

649. But another consideration is necessary to understand clearly what a specific idea is.
The various modes we have mentioned come from defects and imperfections, but in addition to these modes there are modes of the idea itself which originate, not from its defects, but from its manner of being. These modes are as follows.
The pure object of our mind in any perception is a determinate ens (the possibility of something real) (cf. 491). The determinate ens has within itself something by which it is what it is and without which it would not be: this is its first act (cf. 587), immutable and immanent.

This first act produces other acts which are the activities and various actuations of the ens; these can be called second acts because they follow on the first.
These activities and actuations together with their effects and terms remaining in the ens(93) and following on the first act, are not always necessarily joined to the first act; sometimes they can be absent. If they are necessary, they do not have to be of any particular type. For instance, although a body must have a colour (as a quality), the colour is not necessarily blue or red or yellow.

Now, as long as I am thinking of the first act and all it involves as its term, I am still thinking of the ens, because I am thinking of that through which the ens is what it is.
But the first act is not necessarily connected with the many activities and actuations following it, or with their terms, as I have said. Hence, because the act does not involve these, they can be absent or vary, while the ens can continue to be thought.

For example, to be able to think of a human being nothing more is required than what is contained in the definition 'rational animal',(94) because the definition involves the first act by which a human being is a human being, without consideration of any further determinations. Some determinations, such as a particular amount of knowledge, a body of a particular weight and size, are not necessary at all; but if they are necessary in a general way - for example, in the present order of things a human being has weight or extension - then they are already virtually contained in the definition.

If therefore I am thinking of everything included in the first act, I am thinking of the ens; if I am not, then some other ens is the object of my thoughts.
These observations on the nature of many entia suggest the following conclusions: 1. there is something necessary in an ens for it to be what it is, and therefore thinkable; 2. there is something not necessary for it to be thought; and 3. the necessity comes from the intrinsic order of the ens itself.
Let us imagine an ens that has things not necessary for its constitution and existence but necessary for its perfection.
Moreover the things necessary for its perfection are not necessary for my conception of it - for this, it is sufficient to think the act by which it can subsist, since ens is the object of knowledge. If, in my idea, I think of the ens equipped with everything necessary for its possible subsistence but not for its perfection, I have those modes of the idea mentioned above, which derive from its defects.
If I am not thinking of that through which the whole ens exists, I am not thinking that ens.

However, there is another case. I can think of that element in an ens by which it exists, without thinking expressly of the things necessary for its perfection. I do not deny or exclude them. On the contrary I consider them virtually included in the thought of the ens' existence. In this case, I have modes of the specific idea not dependent on defects of the thing but on the particular way I have conceived it and on the ens itself. The ens is such that thinking its root act is sufficient for thinking the ens. These modes therefore of the specific idea are formed by a kind of abstraction. I am not thinking of the defective ens, as in the first modes, nor of the perfect ens, as in the complete idea - I prescind from everything belonging to the ens' perfection and concentrate solely on what makes or can make it subsist.

650. We must also note that because of the imperfection of understanding, human beings can rarely form that full and complete idea of things of which the mode, as we have just described it, is a kind of outline or seed. Thus when they lack the complete specific idea (the type or rather the archetype), they make the abstract idea the foundation of species, an idea which, properly speaking, is only a mode of the full and absolute idea.(95)

651. It is this abstract specific idea that contains what is simply called essence, since the essence of things is only what is thought and presented to our spirit in such an idea.

652. We see that, in the formation of this specific idea, we make use of a kind of abstraction as well as universalisation. However this process does not form species strictly speaking, but only abstract species because the abstract is already understood in the full species. To obtain the full species, we need the integration as well as the universalisation of the imperfect idea we first receive of the thing, although this depends not on the nature of the idea but on the accidental defect of the entia we perceive. This perception gives us our first idea of these entia, an idea we form for ourselves by detaching it from the judgment on their subsistence.

653. Generic ideas are formed by abstraction (cf. 490-503), specific ideas by universalisation alone.(96) Abstraction is a multiple operation; it takes place in different ways and at different levels, and thus provides different types of genera. We must now list these.

654. There are three forms of abstraction, which give us three kinds of generic ideas and generic essences; they can be called real, mental and nominal genera.

655. The origin and distinction of these three kinds of genera begins with the fact that there are two ways in which I can carry out an abstraction on the abstract specific essence. I can abstract something from the essence in such a way that, in the resulting abstract idea, I still think an ens that can be realised; alternatively I can abstract in such a way that I remove everything that constitutes an ens and think only of some mental characteristic, like an accident or a quality, or anything at all that, by itself, does not make an ens known. If the idea still contains an ens, then relative to the specific idea on which I carried out the abstraction, it is a real generic idea. If the idea contains only a mental entity, then it is a mental generic idea. It expresses and presents only an abstract that does not exist outside of thought - at least it does not exist as an ens in the way our mind conceives it.

Take, for example, the idea of human being. This is an abstract specific idea and I can exercise abstraction on it in the two ways indicated.
First, when I abstract the specific difference of reason, the idea is now one of animal. Relative to the species human being,(97) this idea of animal is a real generic idea and includes a real generic essence.

Secondly, I abstract everything constituting an ens and retain only an accident, for example, a colour. Here, the idea of colours is a mental generic idea and, because the abstracted colour is simply an entity of the mind, the essence of colour can be called mental.
We must also note in this case what I have often pointed out: when I am thinking only of abstract accidents, the law of my intelligence, according to which I must think ens, makes me consider those accidents as entia, although I know they are not. Because they are not entia but only a form of the mind, I call them mental or dialectical entia.

656. Finally, in addition to these two ways of abstraction, there is a third way: I can abstract and prescind from both the ens and the accidental qualities, retaining only a relationship, for instance, a sign. Consequently I can arbitrarily impose names and consider them as the foundation of genera. For example, if I were speaking about the genus Smith or the genus Brown, I would call them nominal genera, and their corresponding essence, nominal generic essence.

657. From what has been said, we can gain a more perfect definition of substance in general.
Having examined the difference between abstract specific essence and full specific essence, we said that the first, present to the mind, makes known everything unchangeable in a given determinate ens. Any change would mean the loss of the ens' identity; it would either cease to exist, or become another ens to the mind.
When, in a determinate ens, we think this unchangeable element that constitutes its abstract specific essence, and consider it in relationship to the changeable element united to it in the full specific essence, the abstract specific essence is called substance. It is regarded as the element necessary for the ens to exist, the act by which it subsists and which, as a base, supports the changeable element.
Substance, then, can be defined as 'That by which a determinate ens is what it is', or 'Substance is the abstract specific essence considered in a determinate ens', or 'considered in relationship to the full specific essences of the ens'.

658. If an ens lacked abstract specific essence and had nothing changeable that could be abstracted, any change we might make in it mentally would immediately entail the loss of its identity. If this were the case, the word 'substance' could not be strictly applied to it. We would have to say the whole ens was substance or that its substance was everything found in its full specific essence. This is the case in the divine Being.

659. To conclude: the variety of abstract specific essences is the reason for the variety of substances. Therefore to make the general formula express special substances, we must replace the words 'abstract specific essence in general' with the particular essence that represents the desired substance.(98)

660. Let us return to our argument.

So far we have analysed the concept of substance in order to make it sufficiently clear and distinct, and inconfusable with any other element.
We have seen that if a subject of sensations exists (and its existence was proved in the preceding chapter), it cannot have an existence purely relative to sensations. There has to be something subsisting beforehand, capable of receiving and supporting external sensations (cf. 639-645).

Likewise, if a subject of sensible qualities exists different from the subject of sensations (as the realists claim), it must be an activity that extends not only to providing subsistence for the sensible qualities but is itself something antecedently, and possesses the dispositions called sensible qualities as its own potencies rooted in its being.

After demonstrating that substance or the subject of the accidents, is something existing in itself, an act by which a determinate ens is what it is, I then examined how different substances are specified and distinguished, and found that this was due to the different terms in which the act of being constituting a determinate ens terminates.

I was thus able to perfect the definition of substance further, reducing it to the following general formula: 'Substance is the abstract specific essence considered in a determinate ens.' Then, in order to remove any misunderstanding, I explained essence and its various meanings, amongst which is found abstract, specific essence, the foundation of the substance of an ens.
With the way now clear, I can return to the argument about special substances, and refute Berkeley, as I refuted Hume.
The argument is based on the demonstration, already given, that a substance as subject of sensations (myself) exists. I must still show: 1. that the subject of this substance contains nothing found in the concept of corporeal substance; and 2. that a corporeal substance exists. This latter point, however, will be discussed in the following chapter.

661. There are internal and external sensations. They have a subject, and my consciousness tells me that MYSELF is that subject. We have already seen this in previous discussions.

662. We can all observe this for ourselves. Some effects take place in us without any effort on our part, others take place because we cause them. When I deliberately want something and use my will to obtain it, I feel I am moving myself by my own force, internal to my nature. I am the cause of the actions; I act, I am not passive. When something happens to me without my willing it and even against my will, then I am passive and do not act.

663. It is not a question of whether it is I who am passive when something happens to me nor whether there is any co-operation on my part. What is certain is that, although the action is done in me and I am responsible for the state in which I have to receive it, the activity producing the action is not mine, and I cannot reasonably say that I myself am acting at all. This is not the place to investigate more deeply the nature of passive experience. It is sufficient to indicate the undoubted fact that passive experience exists and is different from the action of our spontaneous will. What has been said is sufficient for my purpose, namely, the necessity of recognising in ourselves two series of events, one in which we justifiably say we are active and another in which we are passive.

664. Among passive occurrences we find sensations that come from outside ourselves; it is these that principally concern us at the moment. We have to recognise sensations as facts taking place in our spirit, which is mainly passive in their regard; it suffers but does not produce an action. Thus, with my eyes fixed on the sun, it is impossible for me not to see its dazzling light and feel its rays on my eyes. If I have not stopped my ears, I hear, even unwillingly, the drums and trumpets of a military band. I feel pain when pricked by a needle, although I prefer not to suffer pain - no one likes pain. In short, if I were not passive to sensations aroused in my body, I could get rid of all harmful ones, have only pleasant ones, and never suffer or die.

665. I mention these particular examples, although more general ones would do, to refute the objection that a person could avoid pain and unwanted sensations by concentrating his attention elsewhere. Objectors claim that even unwanted sensations are due to human action in so far as human beings willingly dispose themselves to receive sense-modifications.

I first reply that human beings cannot avoid all pain because, if that were so, they would be capable of making themselves immortal, or at least of dying without the slightest pain even when a bullet had passed through the heart - which is quite contrary to experience! Second, concentrating our thoughts elsewhere requires great effort on our part and is sometimes so demanding that it is impossible to sustain. The only reason for such a great effort is to avoid pain or any unwanted sensation; in our effort we are using our activity to avoid a hostile force that makes us suffer. But if force is needed to prevent an effect, there must also be an opposing force trying to produce the effect: reaction supposes action, and the force that dominates supposes the force that is dominated. Thus the action we sometimes take to avoid being passive is proof of our passivity.

Finally, we must see if the effort we make to free ourselves of sense-impressions does in fact prevent sensation. Perhaps all we are doing is simply turning our intellective attention from what we are suffering. We can be suffering in our sense-faculty without being conscious of it (we do not perceive our suffering intellectively) and therefore we cannot speak about it. With our attention thus suspended, we no longer think or pass judgment on what we feel.

666. Every fact taking place in us is a modification of our spirit. Thus our spirit is the subject of every fact, as consciousness attests when I say to myself 'I am the one who feels, thinks, decides, is happy or sad', that is, I affirm that I am the subject of all these facts.
However, if we are the subject of passive facts, we are not their cause. As we have said, they do not happen through our action; we suffer and receive them. Anything at all can produce them, against our will or at least without our co-operation.

This distinction between the two series of facts, of one of which we are cause and subject, of the other only subject, is the same as the distinction made above between the series of active and passive facts. The analysis of what is active and of what is passive in us shows that the idea of activity contains the idea of cause and subject, but the idea of passivity only the idea of subject, not that of cause.
Hence the proposition above is contained in the first proposition, which is a fact.

667. At this stage we do not need a complete, final definition of body; it is sufficient to know some of its essential properties to avoid confusing it with anything else. For this purpose the definition we can obtain from what has already been said will suffice.
I use the word 'body' to mean 'the subject of qualities', that is, the subject of those powers that produce sensations in us. Body therefore is the subject of extension, shape, solidity, colour, taste, etc. in so far as these qualities are powers in bodies producing corresponding sensations in us [App., no. 22]. These powers or sensible qualities are the proximate cause of our sensations. So we can define body as 'the proximate cause of sensations and the subject of sensible qualities.' Even if bodies did not exist, it is still true that the definition contains the idea people have of body, and this is what we were seeking.

668. This is a corollary of the preceding propositions. If 'body' is the proximate cause of our external sensations (cf. 667), and if these are facts taking place in us and independently of us, then we are only their passive subject (cf. 666). We have to conclude therefore that Myself is not a body. The word MYSELF expresses a feeling, thinking subject; hence this subject is a substance entirely different from corporeal substance.

669. This reasoning enables us to form a distinct idea of the subject MYSELF. This subject, completely different from body, we call spirit.

670. By indicating the difference and even the opposition between an ens that experiences and an ens that causes experience, I have shown that spirit is something totally different from body. To have shown this is to have demonstrated that spirit is incorporeal.

671. As further proof of the same truth, I will present the arguments of a contemporary Italian philosopher.
I feel what is outside me as multiple.(99) I feel each part of this multiple as distinct from the other parts; in my feeling, the modifications of one part are not those of the others. The trunk of a tree is distinct from its branches, and each branch differs from the others; one branch can move without another moving or without the whole tree moving. This is what is meant by feeling something outside me.
But we must investigate the nature of this feeling of myself which perceives what is outside me. Consciousness of reasoning is perception of myself who reasons.(100) Perception of myself who reasons is perception of myself who says 'therefore', which in turn is perception of myself who judges the inference and the premisses. Myself perceived or felt by consciousness of reasoning is the same myself in each of the three judgments that compose the reasoning. In feeling, therefore, myself that reasons is the same myself that judges, but myself that judges is myself that says 'is' or 'is not'. Consequently, it is myself that perceives the subject and predicate of the judgment. Myself is therefore one in notion, judgment and reasoning.
The subject of a judgment can have both a physical composition and a logical unity. For example, when I say, 'A circle has equal radii', the subject has a physical composition because a circle is multiple;(101) it also has a logical unity because the subject of the judgment is one, and the thought that judges must include the whole circle. Thought therefore makes a circle one; I call this unity of thought 'synthetical unity', that is, unity of synthesis. But to perceive synthetical unity is to perceive myself who synthesises,(102) and to perceive myself who synthesises means to perceive myself who unites the truth of the perceptions of the logical subject.(103) Hence myself, felt by the perception in the synthetical unity, is one despite the variety of perceptions it unites. Myself therefore which begins a reasoning, a demonstration or any science whatever is the same myself that terminates it.
I will try to throw more light on this important truth. Bayle says, 'If a substance which thinks were one only as a globe is one, it would never see a whole tree, never feel pain when beaten by a stick. The following will convince us of this.

'Look at the shapes on a globe of the world. You see nothing on it that contains the whole of Asia or even a whole river or the part representing the kingdom of Siam; the Euphrates is seen to have a left and a right side. Consequently, if the globe were capable of knowing the shapes upon it, nothing on it could say, "I know the whole of Europe, all France, all Amsterdam, the whole Vistula"; each area could know only that part of the shape which falls upon it. Because this part would be so small that it would not represent any place in its entirety, the capacity to know would be absolutely useless to the globe and would not result in any act of knowledge, unless such acts differed vastly from those we experience. Because our acts represent to us a whole tree, a complete horse, it is obvious that the subject acted upon by the full image of these objects is not divisible into many parts. Consequently a human being, as a thinking being, is neither corporeal nor material, or composed of many beings' (Dict., art. Leucippe).

Consciousness of the synthetical unity of perception encompasses therefore the perception of unity or of the simplicity of myself which synthesises. If we think about the comparison that we make between the objects which act on our senses and the judgments caused by their impressions, the feeling of the simple, indivisible, immaterial unity of the thinking being would be obvious. For example, when our hand is warm, we certainly experience one kind of pleasure, but if at the same time our nose smells a pleasant odour, we feel another kind of pleasure. If we are asked which of these two pleasures we like most, the answer is one or the other. We compare them and simultaneously judge them. If, after the warmth and the odour, we taste some food, we can certainly say which of the three pleasures is the greatest; the thing in us that judges must therefore have felt all three objects. Myself that judges knows whether a pleasure of the senses is greater than the pleasure of the discovery of a truth or the pleasure arising from the exercise of virtue, and chooses between them. The same subject which experiences sensible pleasures, also experiences spiritual pleasures, and judges and wills. This is proof that consciousness of myself which feels affected by all these sensations and acts as a result, is by no means consciousness of our nose which senses odours, nor of our hand which feels heat. The hand and nose are two absolutely distinct things; it is just as impossible for one to sense what the other senses as it is for us to sense in this room the pleasure felt by the audience in a theatre. The consciousness I have of myself who simultaneously senses odour and heat includes not only the perception of my nose and hand but also the perception of a single, simple subject that has no parts. If the subject had parts, one part would sense the odour, another the heat; there would never be the feeling of a thing which could simultaneously sense odour and heat, compare them and judge that one is more pleasant than the other.

The feeling of the body is then the feeling of a multiple, of something composed.(104) The feeling of myself is the feeling of what is one, simple and indivisible. One feeling is therefore distinct from the other.
- A science is a sequence of reasonings intended to give us the clearest knowledge possible of any object whatsoever, and reasonings are a series of judgments. No human science would be possible without the direct synthesis of judgment and the indirect synthesis of reasoning. Synthetical unity in reasoning is necessary: there would be no reasoning without 'therefore' just as there would be no judgment without 'is' or 'is not'. In reasoning, 'therefore' binds into a unity of thought the different parts of the reasoning; the 'is' or 'is not' of a judgment binds its different parts into a unity of thought. As I have explained, consciousness of the synthetical unity of thought encompasses consciousness of the unity of the thinking subject. I call this unity of the thinking subject (myself) the metaphysical unity of myself. In other words, the synthetical unity of thought necessarily presupposes the metaphysical unity of myself; they cannot exist without each other. The metaphysical unity of myself is the simplicity or spirituality of the thinking principle. Without it knowledge would be impossible because knowledge presupposes the union of all thoughts composing it. If one thought differed from another, how could their union be effected without a centre of union?(105) How could we become acquainted with the different branches of knowledge without a centre uniting them? A builder must have all the materials necessary for building. Newton's myself which discovers noble calculus is the same myself that learnt arithmetical numeration. Without the metaphysical unity of myself the synthetical unity of thought would be impossible, and without the synthetical unity of thought all human knowledge would be impossible.(106)

(92) There is no need to point out that the father is not the full cause of his son, because a human being cannot make matter exist nor create the human spirit. But the example helps.

(93) For example, inclinations, habits, ideas, objects and terms of thought.

(94) I am not concerned here with judging the merits of this definition; as the one commonly held it is sufficient to illustrate my concept.

(95) The chronological order in which we receive the specific ideas mentioned above, is as follows:

(96) I have called specific ideas (formed only by universalisation), full but imperfect, specific ideas. From them we form, by abstraction, abstract specific ideas, and by integration, complete or perfect specific ideas.

(97) Relative to brute animal, the same idea is specific.

(98) The error of Spinoza's followers consists in taking being for substance. They concluded that because being, as ens, is one, substance must also be one.

(99) It is indeed a fact that I feel many things outside me, although the nature of body does not consist in multiplicity. I have not yet investigated or discovered what body consists of.

(100) Strictly speaking, consciousness of reasoning is not perception of myself who reasons. Perception of myself who reasons contains awareness of reasoning as one of its parts.

(101) It is multiple in potency, that is, it can be distinguished into parts. But if we understand it as a physical not mathematical circle, the reasoning is rigorously correct.

(102) Cf. footnote 99.

(103) It is true that the subject unifies multiple things, but not through its own nature. It does this through the unity of the logical object in which it contemplates these things. From this unity of the logical object (ens), however, the unity of the subject is necessarily induced.

(104) Or at least we certainly perceive many bodies. This is sufficient to demonstrate the unity of the spirit perceiving them.

(105) This centre of union is also a logical object, the foundation and cause of the simplicity of myself that intuits it.

(106) Galluppi, Elementi di filosofia, vol. 3, c. 3, §24-25.