Summa Th. I-II EN Qu.25 a.4

Whether these are the four principal passions: joy, sadness, hope and fear?

504

Objection: 1. It would seem that joy, sadness, hope and fear are not the four principal passions. For Augustine (De Civ. Dei xiv, 3,[7] sqq.) omits hope and puts desire in its place.
2.
Further, there is a twofold order in the passions of the soul: the order of intention, and the order of execution or generation. The principal passions should therefore be taken, either in the order of intention; and thus joy and sadness, which are the final passions, will be the principal passions; or in the order of execution or generation, and thus love will be the principal passion. Therefore joy and sadness, hope and fear should in no way be called the four principal passions.
3.
Further, just as daring is caused by hope, so fear is caused by despair. Either, therefore, hope and despair should be reckoned as principal passions, since they cause others: or hope and daring, from being akin to one another.

On the contrary
Boethius (De Consol. i) in enumerating the four principal passions, says: "Banish joys: banish fears: Away with hope: away with tears."
I answer that
These four are commonly called the principal passions. Two of them, viz. joy and sadness, are said to be principal because in them all the other passions have their completion and end; wherefore they arise from all the other passions, as is stated in Ethic. ii, 5. Fear and hope are principal passions, not because they complete the others simply, but because they complete them as regards the movement of the appetite towards something: for in respect of good, movement begins in love, goes forward to desire, and ends in hope; while in respect of evil, it begins in hatred, goes on to aversion, and ends in fear. Hence it is customary to distinguish these four passions in relation to the present and the future: for movement regards the future, while rest is in something present: so that joy relates to present good, sadness relates to present evil; hope regards future good, and fear, future evil.As to the other passions that regard good or evil, present or future, they all culminate in these four. For this reason some have said that these four are the principal passions, because they are general passions; and this is true, provided that by hope and fear we understand the appetite's common tendency to desire or shun something.

Reply to Objection: 1.
Augustine puts desire or covetousness in place of hope, in so far as they seem to regard the same object, viz. some future good.
2.
These are called principal passions, in the order of intention and completion. And though fear and hope are not the last passions simply, yet they are the last of those passions that tend towards something as future. Nor can the argument be pressed any further except in the case of anger: yet neither can anger be reckoned a principal passion, because it is an effect of daring, which cannot be a principal passion, as we shall state further on (Reply OBJ 3).
3.
Despair implies movement away from good; and this is, as it were, accidental: and daring implies movement towards evil; and this too is accidental. Consequently these cannot be principal passions; because that which is accidental cannot be said to be principal. And so neither can anger be called a principal passion, because it arises from daring.



Q26: OF THE PASSIONS OF THE SOUL IN PARTICULAR: AND FIRST, OF LOVE (FOUR ARTICLES)

520


We have now to consider the soul's passions in particular, and (1) the passions of the concupiscible faculty; (2) the passions of the irascible faculty.

The first of these considerations will be threefold: since we shall consider (1) Love and hatred; (2) Desire and aversion; (3) Pleasure and sadness.

Concerning love, three points must be considered: (1) Love itself; (2) The cause of love; (3) The effects of love. Under the first head there are four points of inquiry:

(1) Whether love is in the concupiscible power?

(2) Whether love is a passion?

(3) Whether love is the same as dilection?

(4) Whether love is properly divided into love of friendship, and love of concupiscence?



Whether love is in the concupiscible power?

521

Objection: 1. It would seem that love is not in the concupiscible power. For it is written (
Sg 8,2): "Her," namely wisdom, "have I loved, and have sought her out from my youth." But the concupiscible power, being a part of the sensitive appetite, cannot tend to wisdom, which is not apprehended by the senses. Therefore love is not in the concupiscible power.
2. Further, love seems to be identified with every passion: for Augustine says (De Civ. Dei xiv, 7): "Love, yearning for the object beloved, is desire; having and enjoying it, is joy; fleeing what is contrary to it, is fear; and feeling what is contrary to it, is sadness." But not every passion is in the concupiscible power; indeed, fear, which is mentioned in this passage, is in the irascible power. Therefore we must not say absolutely that love is in the concupiscible power.
3.
Further, Dionysius (Div. Nom. iv) mentions a "natural love." But natural love seems to pertain rather to the natural powers, which belong to the vegetal soul. Therefore love is not simply in the concupiscible power.

On the contrary
The Philosopher says (Topic. ii, 7) that "love is in the concupiscible power."
I answer that
Love is something pertaining to the appetite; since good is the object of both. Wherefore love differs according to the difference of appetites. For there is an appetite which arises from an apprehension existing, not in the subject of the appetite, but in some other: and this is called the "natural appetite." Because natural things seek what is suitable to them according to their nature, by reason of an apprehension which is not in them, but in the Author of their nature, as stated in the I 6,1, ad 2; I 103,1, ad 1,3. And there is another appetite arising from an apprehension in the subject of the appetite, but from necessity and not from free-will. Such is, in irrational animals, the "sensitive appetite," which, however, in man, has a certain share of liberty, in so far as it obeys reason. Again, there is another appetite following freely from an apprehension in the subject of the appetite. And this is the rational or intellectual appetite, which is called the "will."Now in each of these appetites, the name "love" is given to the principle movement towards the end loved. In the natural appetite the principle of this movement is the appetitive subject's connaturalness with the thing to which it tends, and may be called "natural love": thus the connaturalness of a heavy body for the centre, is by reason of its weight and may be called "natural love." In like manner the aptitude of the sensitive appetite or of the will to some good, that is to say, its very complacency in good is called "sensitive love," or "intellectual" or "rational love." So that sensitive love is in the sensitive appetite, just as intellectual love is in the intellectual appetite. And it belongs to the concupiscible power, because it regards good absolutely, and not under the aspect of difficulty, which is the object of the irascible faculty.

Reply to Objection: 1. The words quoted refer to intellectual or rational love.
2.
Love is spoken of as being fear, joy, desire and sadness, not essentially but causally.
3.
Natural love is not only in the powers of the vegetal soul, but in all the soul's powers, and also in all the parts of the body, and universally in all things: because, as Dionysius says (Div. Nom. iv), "Beauty and goodness are beloved by all things"; since each single thing has a connaturalness with that which is naturally suitable to it.



Whether love is a passion?

522

Objection: 1. It would seem that love is not a passion. For no power is a passion. But every love is a power, as Dionysius says (Div. Nom. iv). Therefore love is not a passion.
2.
Further, love is a kind of union or bond, as Augustine says (De Trin. viii, 10). But a union or bond is not a passion, but rather a relation. Therefore love is not a passion.
3.
Further, Damascene says (De Fide Orth. ii, 22) that passion is a movement. But love does not imply the movement of the appetite; for this is desire, of which movement love is the principle. Therefore love is not a passion.

On the contrary
The Philosopher says (Ethic. viii, 5) that "love is a passion."
I answer that
Passion is the effect of the agent on the patient. Now a natural agent produces a twofold effect on the patient: for in the first place it gives it the form; and secondly it gives it the movement that results from the form. Thus the generator gives the generated body both weight and the movement resulting from weight: so that weight, from being the principle of movement to the place, which is connatural to that body by reason of its weight, can, in a way, be called "natural love." In the same way the appetible object gives the appetite, first, a certain adaptation to itself, which consists in complacency in that object; and from this follows movement towards the appetible object. For "the appetitive movement is circular," as stated in De Anima iii, 10; because the appetible object moves the appetite, introducing itself, as it were, into its intention; while the appetite moves towards the realization of the appetible object, so that the movement ends where it began. Accordingly, the first change wrought in the appetite by the appetible object is called "love," and is nothing else than complacency in that object; and from this complacency results a movement towards that same object, and this movement is "desire"; and lastly, there is rest which is "joy." Since, therefore, love consists in a change wrought in the appetite by the appetible object, it is evident that love is a passion: properly so called, according as it is in the concupiscible faculty; in a wider and extended sense, according as it is in the will.

Reply to Objection: 1.
Since power denotes a principle of movement or action, Dionysius calls love a power, in so far as it is a principle of movement in the appetite.
2.
Union belongs to love in so far as by reason of the complacency of the appetite, the lover stands in relation to that which he loves, as though it were himself or part of himself. Hence it is clear that love is not the very relation of union, but that union is a result of love. Hence, too, Dionysius says that "love is a unitive force" (Div. Nom. iv), and the Philosopher says (Polit. ii, 1) that union is the work of love.
3.
Although love does not denote the movement of the appetite in tending towards the appetible object, yet it denotes that movement whereby the appetite is changed by the appetible object, so as to have complacency therein.



Whether love is the same as dilection?

523

Objection: 1. It would seem that love is the same as dilection. For Dionysius says (Div. Nom. iv) that love is to dilection, "as four is to twice two, and as a rectilinear figure is to one composed of straight lines." But these have the same meaning. Therefore love and dilection denote the same thing.
2.
Further, the movements of the appetite differ by reason of their objects. But the objects of dilection and love are the same. Therefore these are the same.
3.
Further, if dilection and love differ, it seems that it is chiefly in the fact that "dilection refers to good things, love to evil things, as some have maintained," according to Augustine (De Civ. Dei xiv, 7). But they do not differ thus; because as Augustine says (De Civ. Dei xiv, 7) the holy Scripture uses both words in reference to either good or bad things. Therefore love and dilection do not differ: thus indeed Augustine concludes (De Civ. Dei xiv, 7) that "it is not one thing to speak of love, and another to speak of dilection."

On the contrary
Dionysius says (Div. Nom. iv) that "some holy men have held that love means something more Godlike than dilection does."
I answer that
We find four words referring in a way, to the same thing: viz. love, dilection, charity and friendship. They differ, however, in this, that "friendship," according to the Philosopher (Ethic. viii, 5), "is like a habit," whereas "love" and "dilection" are expressed by way of act or passion; and "charity" can be taken either way.Moreover these three express act in different ways. For love has a wider signification than the others, since every dilection or charity is love, but not vice versa. Because dilection implies, in addition to love, a choice [electionem] made beforehand, as the very word denotes: and therefore dilection is not in the concupiscible power, but only in the will, and only in the rational nature. Charity denotes, in addition to love, a certain perfection of love, in so far as that which is loved is held to be of great price, as the word itself implies [*Referring to the Latin "carus" (dear)].

Reply to Objection: 1.
Dionysius is speaking of love and dilection, in so far as they are in the intellectual appetite; for thus love is the same as dilection.
2.
The object of love is more general than the object of dilection: because love extends to more than dilection does, as stated above.
3.
Love and dilection differ, not in respect of good and evil, but as stated. Yet in the intellectual faculty love is the same as dilection. And it is in this sense that Augustine speaks of love in the passage quoted: hence a little further on he adds that "a right will is well-directed love, and a wrong will is ill-directed love." However, the fact that love, which is concupiscible passion, inclines many to evil, is the reason why some assigned the difference spoken of.
4.
The reason why some held that, even when applied to the will itself, the word "love" signifies something more Godlike than "dilection," was because love denotes a passion, especially in so far as it is in the sensitive appetite; whereas dilection presupposes the judgment of reason. But it is possible for man to tend to God by love, being as it were passively drawn by Him, more than he can possibly be drawn thereto by his reason, which pertains to the nature of dilection, as stated above. And consequently love is more Godlike than dilection.



Whether love is properly divided into love of friendship and love of concupiscence?

524

Objection: 1. It would seem that love is not properly divided into love of friendship and love of concupiscence. For "love is a passion, while friendship is a habit," according to the Philosopher (Ethic. viii, 5). But habit cannot be the member of a division of passions. Therefore love is not properly divided into love of concupiscence and love of friendship.
2.
Further, a thing cannot be divided by another member of the same division; for man is not a member of the same division as "animal." But concupiscence is a member of the same division as love, as a passion distinct from love. Therefore concupiscence is not a division of love.
3.
Further, according to the Philosopher (Ethic. viii, 3) friendship is threefold, that which is founded on "usefulness," that which is founded on "pleasure," and that which is founded on "goodness." But useful and pleasant friendship are not without concupiscence. Therefore concupiscence should not be contrasted with friendship.

On the contrary
We are said to love certain things, because we desire them: thus "a man is said to love wine, on account of its sweetness which he desires"; as stated in Topic. ii, 3. But we have no friendship for wine and suchlike things, as stated in Ethic. viii, 2. Therefore love of concupiscence is distinct from love of friendship.
I answer that
As the Philosopher says (Rhet. ii, 4), "to love is to wish good to someone." Hence the movement of love has a twofold tendency: towards the good which a man wishes to someone (to himself or to another) and towards that to which he wishes some good. Accordingly, man has love of concupiscence towards the good that he wishes to another, and love of friendship towards him to whom he wishes good.Now the members of this division are related as primary and secondary: since that which is loved with the love of friendship is loved simply and for itself; whereas that which is loved with the love of concupiscence, is loved, not simply and for itself, but for something else. For just as that which has existence, is a being simply, while that which exists in another is a relative being; so, because good is convertible with being, the good, which itself has goodness, is good simply; but that which is another's good, is a relative good. Consequently the love with which a thing is loved, that it may have some good, is love simply; while the love, with which a thing is loved, that it may be another's good, is relative love.

Reply to Objection: 1.
Love is not divided into friendship and concupiscence, but into love of friendship, and love of concupiscence. For a friend is, properly speaking, one to whom we wish good: while we are said to desire, what we wish for ourselves.
2.
Hence the Reply to the Second Objection.
3.
When friendship is based on usefulness or pleasure, a man does indeed wish his friend some good: and in this respect the character of friendship is preserved. But since he refers this good further to his own pleasure or use, the result is that friendship of the useful or pleasant, in so far as it is connected with love of concupiscence, loses the character to true friendship.



Q27: OF THE CAUSE OF LOVE (FOUR ARTICLES)

540


We must now consider the cause of love: and under this head there are four points of inquiry:

(1) Whether good is the only cause of love?

(2) Whether knowledge is a cause of love?

(3) Whether likeness is a cause of love?

(4) Whether any other passion of the soul is a cause of love?



Whether good is the only cause of love?

541

Objection: 1. It would seem that good is not the only cause of love. For good does not cause love, except because it is loved. But it happens that evil also is loved, according to
Ps 10,6: "He that loveth iniquity, hateth his own soul": else, every love would be good. Therefore good is not the only cause of love.
2. Further, the Philosopher says (Rhet. ii, 4) that "we love those who acknowledge their evils." Therefore it seems that evil is the cause of love.
3.
Further, Dionysius says (Div. Nom. iv) that not "the good" only but also "the beautiful is beloved by all."

On the contrary
Augustine says (De Trin. viii, 3): "Assuredly the good alone is beloved." Therefore good alone is the cause of love.
I answer that
As stated above (Question [26], Article [1]), Love belongs to the appetitive power which is a passive faculty. Wherefore its object stands in relation to it as the cause of its movement or act. Therefore the cause of love must needs be love's object. Now the proper object of love is the good; because, as stated above (Question [26], Articles [1],2), love implies a certain connaturalness or complacency of the lover for the thing beloved, and to everything, that thing is a good, which is akin and proportionate to it. It follows, therefore, that good is the proper cause of love.

Reply to Objection: 1.
Evil is never loved except under the aspect of good, that is to say, in so far as it is good in some respect, and is considered as being good simply. And thus a certain love is evil, in so far as it tends to that which is not simply a true good. It is in this way that man "loves iniquity," inasmuch as, by means of iniquity, some good is gained; pleasure, for instance, or money, or such like.
2.
Those who acknowledge their evils, are beloved, not for their evils, but because they acknowledge them, for it is a good thing to acknowledge one's faults, in so far as it excludes insincerity or hypocrisy.
3.
The beautiful is the same as the good, and they differ in aspect only. For since good is what all seek, the notion of good is that which calms the desire; while the notion of the beautiful is that which calms the desire, by being seen or known. Consequently those senses chiefly regard the beautiful, which are the most cognitive, viz. sight and hearing, as ministering to reason; for we speak of beautiful sights and beautiful sounds. But in reference to the other objects of the other senses, we do not use the expression "beautiful," for we do not speak of beautiful tastes, and beautiful odors. Thus it is evident that beauty adds to goodness a relation to the cognitive faculty: so that "good" means that which simply pleases the appetite; while the "beautiful" is something pleasant to apprehend.



Whether knowledge is a cause of love?

542

Objection: 1. It would seem that knowledge is not a cause of love. For it is due to love that a thing is sought. But some things are sought without being known, for instance, the sciences; for since "to have them is the same as to know them," as Augustine says (Questions [83], qu. 35), if we knew them we should have them, and should not seek them. Therefore knowledge is not the cause of love.
2.
Further, to love what we know not seems like loving something more than we know it. But some things are loved more than they are known: thus in this life God can be loved in Himself, but cannot be known in Himself. Therefore knowledge is not the cause of love.
3.
Further, if knowledge were the cause of love, there would be no love, where there is no knowledge. But in all things there is love, as Dionysius says (Div. Nom. iv); whereas there is not knowledge in all things. Therefore knowledge is not the cause of love.

On the contrary
Augustine proves (De Trin. x, 1,2) that "none can love what he does not know."
I answer that
As stated above (Article [1]), good is the cause of love, as being its object. But good is not the object of the appetite, except as apprehended. And therefore love demands some apprehension of the good that is loved. For this reason the Philosopher (Ethic. ix, 5,12) says that bodily sight is the beginning of sensitive love: and in like manner the contemplation of spiritual beauty or goodness is the beginning of spiritual love. Accordingly knowledge is the cause of love for the same reason as good is, which can be loved only if known.

Reply to Objection: 1.
He who seeks science, is not entirely without knowledge thereof: but knows something about it already in some respect, either in a general way, or in some one of its effects, or from having heard it commended, as Augustine says (De Trin. x, 1,2). But to have it is not to know it thus, but to know it perfectly.
2.
Something is required for the perfection of knowledge, that is not requisite for the perfection of love. For knowledge belongs to the reason, whose function it is to distinguish things which in reality are united, and to unite together, after a fashion, things that are distinct, by comparing one with another. Consequently the perfection of knowledge requires that man should know distinctly all that is in a thing, such as its parts, powers, and properties. On the other hand, love is in the appetitive power, which regards a thing as it is in itself: wherefore it suffices, for the perfection of love, that a thing be loved according as it is known in itself. Hence it is, therefore, that a thing is loved more than it is known; since it can be loved perfectly, even without being perfectly known. This is most evident in regard to the sciences, which some love through having a certain general knowledge of them: for instance, they know that rhetoric is a science that enables man to persuade others; and this is what they love in rhetoric. The same applies to the love of God.
3.
Even natural love, which is in all things, is caused by a kind of knowledge, not indeed existing in natural things themselves, but in Him Who created their nature, as stated above (Question [26], Article [1]; cf. I 6,1, ad 2).



Whether likeness is a cause of love?

543

Objection: 1. It would seem that likeness is not a cause of love. For the same thing is not the cause of contraries. But likeness is the cause of hatred; for it is written (
Pr 13,10) that "among the proud there are always contentions"; and the Philosopher says (Ethic. viii, 1) that "potters quarrel with one another." Therefore likeness is not a cause of love.
2. Further, Augustine says (Confess. iv, 14) that "a man loves in another that which he would not be himself: thus he loves an actor, but would not himself be an actor." But it would not be so, if likeness were the proper cause of love; for in that case a man would love in another, that which he possesses himself, or would like to possess. Therefore likeness is not a cause of love.
3.
Further, everyone loves that which he needs, even if he have it not: thus a sick man loves health, and a poor man loves riches. But in so far as he needs them and lacks them, he is unlike them. Therefore not only likeness but also unlikeness is a cause of love.
4.
Further, the Philosopher says (Rhet. ii, 4) that "we love those who bestow money and health on us; and also those who retain their friendship for the dead." But all are not such. Therefore likeness is not a cause of love.

On the contrary
It is written (Si 13,19): "Every beast loveth its like."
I answer that Likeness, properly speaking, is a cause of love. But it must be observed that likeness between things is twofold. One kind of likeness arises from each thing having the same quality actually: for example, two things possessing the quality of whiteness are said to be alike. Another kind of likeness arises from one thing having potentially and by way of inclination, a quality which the other has actually: thus we may say that a heavy body existing outside its proper place is like another heavy body that exists in its proper place: or again, according as potentiality bears a resemblance to its act; since act is contained, in a manner, in the potentiality itself.Accordingly the first kind of likeness causes love of friendship or well-being. For the very fact that two men are alike, having, as it were, one form, makes them to be, in a manner, one in that form: thus two men are one thing in the species of humanity, and two white men are one thing in whiteness. Hence the affections of one tend to the other, as being one with him; and he wishes good to him as to himself. But the second kind of likeness causes love of concupiscence, or friendship founded on usefulness or pleasure: because whatever is in potentiality, as such, has the desire for its act; and it takes pleasure in its realization, if it be a sentient and cognitive being.Now it has been stated above (Question [26], Article [4]), that in the love of concupiscence, the lover, properly speaking, loves himself, in willing the good that he desires. But a man loves himself more than another: because he is one with himself substantially, whereas with another he is one only in the likeness of some form. Consequently, if this other's likeness to him arising from the participation of a form, hinders him from gaining the good that he loves, he becomes hateful to him, not for being like him, but for hindering him from gaining his own good. This is why "potters quarrel among themselves," because they hinder one another's gain: and why "there are contentions among the proud," because they hinder one another in attaining the position they covet.

Objection: 1. Hence the Reply to the First Objection is evident.
2.
Even when a man loves in another what he loves not in himself, there is a certain likeness of proportion: because as the latter is to that which is loved in him, so is the former to that which he loves in himself: for instance, if a good singer love a good writer, we can see a likeness of proportion, inasmuch as each one has that which is becoming to him in respect of his art.
3.
He that loves what he needs, bears a likeness to what he loves, as potentiality bears a likeness to its act, as stated above.
4.
According to the same likeness of potentiality to its act, the illiberal man loves the man who is liberal, in so far as he expects from him something which he desires. The same applies to the man who is constant in his friendship as compared to one who is inconstant. For in either case friendship seems to be based on usefulness. We might also say that although not all men have these virtues in the complete habit, yet they have them according to certain seminal principles in the reason, in force of which principles the man who is not virtuous loves the virtuous man, as being in conformity with his own natural reason.



Whether any other passion of the soul is a cause of love?

544

Objection: 1. It would seem that some other passion can be the cause of love. For the Philosopher (Ethic. viii, 3) says that some are loved for the sake of the pleasure they give. But pleasure is a passion. Therefore another passion is a cause of love.
2.
Further, desire is a passion. But we love some because we desire to receive something from them: as happens in every friendship based on usefulness. Therefore another passion is a cause of love.
3.
Further, Augustine says (De Trin. x, 1): "When we have no hope of getting a thing, we love it but half-heartedly or not at all, even if we see how beautiful it is." Therefore hope too is a cause of love.

On the contrary
All the other emotions of the soul are caused by love, as Augustine says (De Civ. Dei xiv, 7,9).
I answer that
There is no other passion of the soul that does not presuppose love of some kind. The reason is that every other passion of the soul implies either movement towards something, or rest in something. Now every movement towards something, or rest in something, arises from some kinship or aptness to that thing; and in this does love consist. Therefore it is not possible for any other passion of the soul to be universally the cause of every love. But it may happen that some other passion is the cause of some particular love: just as one good is the cause of another.

Reply to Objection: 1.
When a man loves a thing for the pleasure it affords, his love is indeed caused by pleasure; but that very pleasure is caused, in its turn, by another preceding love; for none takes pleasure save in that which is loved in some way.
2.
Desire for a thing always presupposes love for that thing. But desire of one thing can be the cause of another thing's being loved; thus he that desires money, for this reason loves him from whom he receives it.
3.
Hope causes or increases love; both by reason of pleasure, because it causes pleasure; and by reason of desire, because hope strengthens desire, since we do not desire so intensely that which we have no hope of receiving. Nevertheless hope itself is of a good that is loved.



Q28: OF THE EFFECTS OF LOVE (SIX ARTICLES)

560


We now have to consider the effects of love: under which head there are six points of inquiry:

(1) Whether union is an effect of love?

(2) Whether mutual indwelling is an effect of love?

(3) Whether ecstasy is an effect of love?

(4) Whether zeal is an effect of love?

(5) Whether love is a passion that is hurtful to the lover?

(6) Whether love is cause of all that the lover does?

Whether union is an effect of love?

561

Objection: 1. It would seem that union is not an effect of love. For absence is incompatible with union. But love is compatible with absence; for the Apostle says (
Ga 4,18): "Be zealous for that which is good in a good thing always" (speaking of himself, according to a gloss), "and not only when I am present with you." Therefore union is not an effect of love.
2. Further, every union is either according to essence, thus form is united to matter, accident to subject, and a part to the whole, or to another part in order to make up the whole: or according to likeness, in genus, species, or accident. But love does not cause union of essence; else love could not be between things essentially distinct. On the other hand, love does not cause union of likeness, but rather is caused by it, as stated above (Question [27], Article [3]). Therefore union is not an effect of love.
3.
Further, the sense in act is the sensible in act, and the intellect in act is the thing actually understood. But the lover in act is not the beloved in act. Therefore union is the effect of knowledge rather than of love.

On the contrary
Dionysius says (Div. Nom. iv) that every love is a "unitive love."
I answer that
The union of lover and beloved is twofold. The first is real union; for instance, when the beloved is present with the lover. The second is union of affection: and this union must be considered in relation to the preceding apprehension; since movement of the appetite follows apprehension. Now love being twofold, viz. love of concupiscence and love of friendship; each of these arises from a kind of apprehension of the oneness of the thing loved with the lover. For when we love a thing, by desiring it, we apprehend it as belonging to our well-being. In like manner when a man loves another with the love of friendship, he wills good to him, just as he wills good to himself: wherefore he apprehends him as his other self, in so far, to wit, as he wills good to him as to himself. Hence a friend is called a man's "other self" (Ethic. ix, 4), and Augustine says (Confess. iv, 6), "Well did one say to his friend: Thou half of my soul."The first of these unions is caused "effectively" by love; because love moves man to desire and seek the presence of the beloved, as of something suitable and belonging to him. The second union is caused "formally" by love; because love itself is this union or bond. In this sense Augustine says (De Trin. viii, 10) that "love is a vital principle uniting, or seeking to unite two together, the lover, to wit, and the beloved." For in describing it as "uniting" he refers to the union of affection, without which there is no love: and in saying that "it seeks to unite," he refers to real union.

Reply to Objection: 1.
This argument is true of real union. That is necessary to pleasure as being its cause; desire implies the real absence of the beloved: but love remains whether the beloved be absent or present.
2.
Union has a threefold relation to love. There is union which causes love; and this is substantial union, as regards the love with which one loves oneself; while as regards the love wherewith one loves other things, it is the union of likeness, as stated above (Question [27], Article [3]). There is also a union which is essentially love itself. This union is according to a bond of affection, and is likened to substantial union, inasmuch as the lover stands to the object of his love, as to himself, if it be love of friendship; as to something belonging to himself, if it be love of concupiscence. Again there is a union, which is the effect of love. This is real union, which the lover seeks with the object of his love. Moreover this union is in keeping with the demands of love: for as the Philosopher relates (Polit. ii, 1), "Aristophanes stated that lovers would wish to be united both into one," but since "this would result in either one or both being destroyed," they seek a suitable and becoming union---to live together, speak together, and be united together in other like things.
3.
Knowledge is perfected by the thing known being united, through its likeness, to the knower. But the effect of love is that the thing itself which is loved, is, in a way, united to the lover, as stated above. Consequently the union caused by love is closer than that which is caused by knowledge.




Summa Th. I-II EN Qu.25 a.4