Summa Th. I-II EN Qu.47 a.4
944
Objection: 1. It would seem that a person's defect is not a reason for being more easily angry with him. For the Philosopher says (Rhet. ii, 3) that "we are not angry with those who confess and repent and humble themselves; on the contrary, we are gentle with them. Wherefore dogs bite not those who sit down." But these things savor of littleness and defect. Therefore littleness of a person is a reason for being less angry with him.
2. Further, there is no greater defect than death. But anger ceases at the sight of death. Therefore defect of a person does not provoke anger against him.
3. Further, no one thinks little of a man through his being friendly towards him. But we are more angry with friends, if they offend us or refuse to help us; hence it is written (Ps 54,13): "If my enemy had reviled me I would verily have borne with it." Therefore a person's defect is not a reason for being more easily angry with him.
On the contrary The Philosopher says (Rhet. ii, 2) that "the rich man is angry with the poor man, if the latter despise him; and in like manner the prince is angry with his subject."
I answer that As stated above (Articles [2],3) unmerited contempt more than anything else is a provocative of anger. Consequently deficiency or littleness in the person with whom we are angry, tends to increase our anger, in so far as it adds to the unmeritedness of being despised. For just as the higher a man's position is, the more undeservedly he is despised; so the lower it is, the less reason he has for despising. Thus a nobleman is angry if he be insulted by a peasant; a wise man, if by a fool; a master, if by a servant.If, however, the littleness or deficiency lessens the unmerited contempt, then it does not increase but lessens anger. In this way those who repent of their ill-deeds, and confess that they have done wrong, who humble themselves and ask pardon, mitigate anger, according to Pr 15,1: "A mild answer breaketh wrath": because, to wit, they seem not to despise, but rather to think much of those before whom they humble themselves.
Reply to Objection: 1. This suffices for the Reply to the First Objection.
2. There are two reasons why anger ceases at the sight of death. One is because the dead are incapable of sorrow and sensation; and this is chiefly what the angry seek in those with whom they are angered. Another reason is because the dead seem to have attained to the limit of evils. Hence anger ceases in regard to all who are grievously hurt, in so far as this hurt surpasses the measure of just retaliation.
3. To be despised by one's friends seems also a greater indignity. Consequently if they despise us by hurting or by failing to help, we are angry with them for the same reason for which we are angry with those who are beneath us.
960
We must now consider the effects of anger: under which head there are four points of inquiry:
(1) Whether anger causes pleasure?
(2) Whether above all it causes heat in the heart?
(3) Whether above all it hinders the use of reason?
(4) Whether it causes taciturnity?
961
Objection: 1. It would seem that anger does not cause pleasure. Because sorrow excludes pleasure. But anger is never without sorrow, since, as stated in Ethic. vii, 6, "everyone that acts from anger, acts with pain." Therefore anger does not cause pleasure.
2. Further, the Philosopher says (Ethic. iv, 5) that "vengeance makes anger to cease, because it substitutes pleasure for pain": whence we may gather that the angry man derives pleasure from vengeance, and that vengeance quells his anger. Therefore on the advent of pleasure, anger departs: and consequently anger is not an effect united with pleasure.
3. Further, no effect hinders its cause, since it is conformed to its cause. But pleasure hinders anger as stated in Rhet. ii, 3. Therefore pleasure is not an effect of anger.
On the contrary The Philosopher (Ethic. iv, 5) quotes the saying that anger is "Sweet to the soul as honey to the taste" (Iliad, xviii, 109 [trl. Pope]).
I answer that As the Philosopher says (Ethic. vii, 14), pleasures, chiefly sensible and bodily pleasures, are remedies against sorrow: and therefore the greater the sorrow or anxiety, the more sensible are we to the pleasure which heals it, as is evident in the case of thirst which increases the pleasure of drink. Now it is clear from what has been said (Question [47], Articles [1],3), that the movement of anger arises from a wrong done that causes sorrow, for which sorrow vengeance is sought as a remedy. Consequently as soon as vengeance is present, pleasure ensues, and so much the greater according as the sorrow was greater. Therefore if vengeance be really present, perfect pleasure ensues, entirely excluding sorrow, so that the movement of anger ceases. But before vengeance is really present, it becomes present to the angry man in two ways: in one way, by hope; because none is angry except he hopes for vengeance, as stated above (Question [46], Article [1]); in another way, by thinking of it continually, for to everyone that desires a thing it is pleasant to dwell on the thought of what he desires; wherefore the imaginings of dreams are pleasant. Accordingly an angry man takes pleasure in thinking much about vengeance. This pleasure, however, is not perfect, so as to banish sorrow and consequently anger.
Reply to Objection: 1. The angry man does not grieve and rejoice at the same thing; he grieves for the wrong done, while he takes pleasure in the thought and hope of vengeance. Consequently sorrow is to anger as its beginning; while pleasure is the effect or terminus of anger.
2. This argument holds in regard to pleasure caused by the real presence of vengeance, which banishes anger altogether.
3. Pleasure that precedes hinders sorrow from ensuing, and consequently is a hindrance to anger. But pleasure felt in taking vengeance follows from anger.
962
Objection: 1. It would seem that heat is not above all the effect of anger. For fervor, as stated above (Question [28], Article [5]; Question [37], Article [2]), belongs to love. But love, as above stated, is the beginning and cause of all the passions. Since then the cause is more powerful than its effect, it seems that anger is not the chief cause of fervor.
2. Further, those things which, of themselves, arouse fervor, increase as time goes on; thus love grows stronger the longer it lasts. But in course of time anger grows weaker; for the Philosopher says (Rhet. ii, 3) that "time puts an end to anger." Therefore fervor is not the proper effect of anger.
3. Further, fervor added to fervor produces greater fervor. But "the addition of a greater anger banishes already existing anger," as the Philosopher says (Rhet. ii, 3). Therefore anger does not cause fervor.
On the contrary Damascene says (De Fide Orth. ii, 16) that "anger is fervor of the blood around the heart, resulting from an exhalation of the bile."
I answer that As stated above (Question [44], Article [1]), the bodily transmutation that occurs in the passions of the soul is proportionate to the movement of the appetite. Now it is evident that every appetite, even the natural appetite, tends with greater force to repel that which is contrary to it, if it be present: hence we see that hot water freezes harder, as though the cold acted with greater force on the hot object. Since then the appetitive movement of anger is caused by some injury inflicted, as by a contrary that is present; it follows that the appetite tends with great force to repel the injury by the desire of vengeance; and hence ensues great vehemence and impetuosity in the movement of anger. And because the movement of anger is not one of recoil, which corresponds to the action of cold, but one of prosecution, which corresponds to the action of heat, the result is that the movement of anger produces fervor of the blood and vital spirits around the heart, which is the instrument of the soul's passions. And hence it is that, on account of the heart being so disturbed by anger, those chiefly who are angry betray signs thereof in their outer members. For, as Gregory says (Moral. v, 30) "the heart that is inflamed with the stings of its own anger beats quick, the body trembles, the tongue stammers, the countenance takes fire, the eyes grow fierce, they that are well known are not recognized. With the mouth indeed he shapes a sound, but the understanding knows not what it says."
Reply to Objection: 1. "Love itself is not felt so keenly as in the absence of the beloved," as Augustine observes (De Trin. x, 12). Consequently when a man suffers from a hurt done to the excellence that he loves, he feels his love thereof the more: the result being that his heart is moved with greater heat to remove the hindrance to the object of his love; so that anger increases the fervor of love and makes it to be felt more.Nevertheless, the fervor arising from heat differs according as it is to be referred to love or to anger. Because the fervor of love has a certain sweetness and gentleness; for it tends to the good that one loves: whence it is likened to the warmth of the air and of the blood. For this reason sanguine temperaments are more inclined to love; and hence the saying that "love springs from the liver," because of the blood being formed there. On the other hand, the fervor of anger has a certain bitterness with a tendency to destroy, for it seeks to be avenged on the contrary evil: whence it is likened to the heat of fire and of the bile, and for this reason Damascene says (De Fide Orth. ii, 16) that it "results from an exhalation of the bile whence it takes its name (chole)."
2. Time, of necessity, weakens all those things, the causes of which are impaired by time. Now it is evident that memory is weakened by time; for things which happened long ago easily slip from our memory. But anger is caused by the memory of a wrong done. Consequently the cause of anger is impaired little by little as time goes on, until at length it vanishes altogether. Moreover a wrong seems greater when it is first felt; and our estimate thereof is gradually lessened the further the sense of present wrong recedes into the past. The same applies to love, so long as the cause of love is in the memory alone; wherefore the Philosopher says (Ethic. viii, 5) that "if a friend's absence lasts long, it seems to make men forget their friendship." But in the presence of a friend, the cause of friendship is continually being multiplied by time: wherefore the friendship increases: and the same would apply to anger, were its cause continually multiplied.Nevertheless the very fact that anger soon spends itself proves the strength of its fervor: for as a great fire is soon spent having burnt up all the fuel; so too anger, by reason of its vehemence, soon dies away.
3. Every power that is divided in itself is weakened. Consequently if a man being already angry with one, becomes angry with another, by this very fact his anger with the former is weakened. Especially is this so if his anger in the second case be greater: because the wrong done which aroused his former anger, will, in comparison with the second wrong, which is reckoned greater, seem to be of little or no account.
963
Objection: 1. It would seem that anger does not hinder the use of reason. Because that which presupposes an act of reason, does not seem to hinder the use of reason. But "anger listens to reason," as stated in Ethic. vii, 6. Therefore anger does not hinder reason.
2. Further, the more the reason is hindered, the less does a man show his thoughts. But the Philosopher says (Ethic. vii, 6) that "an angry man is not cunning but is open." Therefore anger does not seem to hinder the use of reason, as desire does; for desire is cunning, as he also states (Ethic. vii, 6.).
3. Further, the judgment of reason becomes more evident by juxtaposition of the contrary: because contraries stand out more clearly when placed beside one another. But this also increases anger: for the Philosopher says (Rhet. ii, 2) that "men are more angry if they receive unwonted treatment; for instance, honorable men, if they be dishonored": and so forth. Therefore the same cause increases anger, and facilitates the judgment of reason. Therefore anger does not hinder the judgment of reason.
On the contrary Gregory says (Moral. v, 30) that anger "withdraws the light of understanding, while by agitating it troubles the mind."
I answer that Although the mind or reason makes no use of a bodily organ in its proper act, yet, since it needs certain sensitive powers for the execution of its act, the acts of which powers are hindered when the body is disturbed, it follows of necessity that any disturbance in the body hinders even the judgment of reason; as is clear in the case of drunkenness or sleep. Now it has been stated (Article [2]) that anger, above all, causes a bodily disturbance in the region of the heart, so much as to effect even the outward members. Consequently, of all the passions, anger is the most manifest obstacle to the judgment of reason, according to Ps 30,10: "My eye is troubled with wrath."
Reply to Objection: 1. The beginning of anger is in the reason, as regards the appetitive movement, which is the formal element of anger. But the passion of anger forestalls the perfect judgment of reason, as though it listened but imperfectly to reason, on account of the commotion of the heat urging to instant action, which commotion is the material element of anger. In this respect it hinders the judgment of reason.
2. An angry man is said to be open, not because it is clear to him what he ought to do, but because he acts openly, without thought of hiding himself. This is due partly to the reason being hindered, so as not to discern what should be hidden and what done openly, nor to devise the means of hiding; and partly to the dilatation of the heart which pertains to magnanimity which is an effect of anger: wherefore the Philosopher says of the magnanimous man (Ethic. iv, 3) that "he is open in his hatreds and his friendships . . . and speaks and acts openly." Desire, on the other hand, is said to lie low and to be cunning, because, in many cases, the pleasurable things that are desired, savor of shame and voluptuousness, wherein man wishes not to be seen. But in those things that savor of manliness and excellence, such as matters of vengeance, man seeks to be in the open.
3. As stated above (ad 1), the movement of anger begins in the reason, wherefore the juxtaposition of one contrary with another facilitates the judgment of reason, on the same grounds as it increases anger. For when a man who is possessed of honor or wealth, suffers a loss therein, the loss seems all the greater, both on account of the contrast, and because it was unforeseen. Consequently it causes greater grief: just as a great good, through being received unexpectedly, causes greater delight. And in proportion to the increase of the grief that precedes, anger is increased also.
964
Objection: 1. It would seem that anger does not cause taciturnity. Because taciturnity is opposed to speech. But increase in anger conduces to speech; as is evident from the degrees of anger laid down by Our Lord (Mt 5,22): where He says: "Whosoever is angry with his brother"; and " . . . whosoever shall say to his brother, 'Raca'"; and " . . . whosoever shall say to his brother, 'Thou fool.'" Therefore anger does not cause taciturnity.
2. Further, through failing to obey reason, man sometimes breaks out into unbecoming words: hence it is written (Pr 25,28): "As a city that lieth open and is not compassed with walls, so is a man that cannot refrain his own spirit in speaking." But anger, above all, hinders the judgment of reason, as stated above (Article [3]). Consequently above all it makes one break out into unbecoming words. Therefore it does not cause taciturnity.
3. Further, it is written (Mt 12,34): "Out of the abundance of the heart the mouth speaketh." But anger, above all, causes a disturbance in the heart, as stated above (Article [2]). Therefore above all it conduces to speech. Therefore it does not cause taciturnity.
On the contrary Gregory says (Moral. v, 30) that "when anger does not vent itself outwardly by the lips, inwardly it burns the more fiercely."
I answer that As stated above (Article [3]; Question [46], Article [4]), anger both follows an act of reason, and hinders the reason: and in both respects it may cause taciturnity. On the part of the reason, when the judgment of reason prevails so far, that although it does not curb the appetite in its inordinate desire for vengeance, yet it curbs the tongue from unbridled speech. Wherefore Gregory says (Moral. v, 30): "Sometimes when the mind is disturbed, anger, as if in judgment, commands silence." On the part of the impediment to reason because, as stated above (Article [2]), the disturbance of anger reaches to the outward members, and chiefly to those members which reflect more distinctly the emotions of the heart, such as the eyes, face and tongue; wherefore, as observed above (Article [2]), "the tongue stammers, the countenance takes fire, the eyes grow fierce." Consequently anger may cause such a disturbance, that the tongue is altogether deprived of speech; and taciturnity is the result.
Reply to Objection: 1. Anger sometimes goes so far as to hinder the reason from curbing the tongue: but sometimes it goes yet farther, so as to paralyze the tongue and other outward members.
2. And this suffices for the Reply to the Second Objection.
3. The disturbance of the heart may sometimes superabound to the extend that the movements of the outward members are hindered by the inordinate movement of the heart. Thence ensue taciturnity and immobility of the outward members; and sometimes even death. If, however, the disturbance be not so great, then "out of the abundance of the heart" thus disturbed, the mouth proceeds to speak.
TREATISE ON HABITS (Questions [49]-54)
980
After treating of human acts and passions, we now pass on to the consideration of the principles of human acts, and firstly of intrinsic principles, secondly of extrinsic principles. The intrinsic principle is power and habit; but as we have treated of powers in the I 77,0, seqq., it remains for us to consider them in general: in the second place we shall consider virtues and vices and other like habits, which are the principles of human acts.
Concerning habits in general there are four points to consider: First, the substance of habits; second, their subject; third, the cause of their generation, increase, and corruption; fourth, how they are distinguished from one another.
Under the first head, there are four points of inquiry:
(1) Whether habit is a quality?
(2) Whether it is a distinct species of quality?
(3) Whether habit implies an order to an act?
(4) Of the necessity of habit.
981
Objection: 1. It would seem that habit is not a quality. For Augustine says (Questions. lxxxiii, qu. 73): "this word 'habit' is derived from the verb 'to have.'" But "to have" belongs not only to quality, but also to the other categories: for we speak of ourselves as "having" quantity and money and other like things. Therefore habit is not a quality.
2. Further, habit is reckoned as one of the predicaments; as may be clearly seen in the Book of the Predicaments (Categor. vi). But one predicament is not contained under another. Therefore habit is not a quality.
3. Further, "every habit is a disposition," as is stated in the Book of the Predicaments (Categor. vi). Now disposition is "the order of that which has parts," as stated in Metaph. v, text. 24. But this belongs to the predicament Position. Therefore habit is not a quality.
On the contrary The Philosopher says in the Book of Predicaments (Categor. vi) that "habit is a quality which is difficult to change."
I answer that This word "habitus" [habit] is derived from "habere" [to have]. Now habit is taken from this word in two ways; in one way, inasmuch as man, or any other thing, is said to "have" something; in another way, inasmuch as a particular thing has a relation [se habet] either in regard to itself, or in regard to something else.Concerning the first, we must observe that "to have," as said in regard to anything that is "had," is common to the various predicaments. And so the Philosopher puts "to have" among the "post-predicaments," so called because they result from the various predicaments; as, for instance, opposition, priority, posterity, and such like. Now among things which are had, there seems to be this distinction, that there are some in which there is no medium between the "haver" and that which is had: as, for instance, there is no medium between the subject and quality or quantity. Then there are some in which there is a medium, but only a relation: as, for instance, a man is said to have a companion or a friend. And, further, there are some in which there is a medium, not indeed an action or passion, but something after the manner of action or passion: thus, for instance, something adorns or covers, and something else is adorned or covered: wherefore the Philosopher says (Metaph. v, text. 25) that "a habit is said to be, as it were, an action or a passion of the haver and that which is had"; as is the case in those things which we have about ourselves. And therefore these constitute a special genus of things, which are comprised under the predicament of "habit": of which the Philosopher says (Metaph. v, text. 25) that "there is a habit between clothing and the man who is clothed."But if "to have" be taken according as a thing has a relation in regard to itself or to something else; in that case habit is a quality; since this mode of having is in respect of some quality: and of this the Philosopher says (Metaph. v, text. 25) that "habit is a disposition whereby that which is disposed is disposed well or ill, and this, either in regard to itself or in regard to another: thus health is a habit." And in this sense we speak of habit now. Wherefore we must say that habit is a quality.
Reply to Objection: 1. This argument takes "to have" in the general sense: for thus it is common to many predicaments, as we have said.
2. This argument takes habit in the sense in which we understand it to be a medium between the haver, and that which is had: and in this sense it is a predicament, as we have said.
3. Disposition does always, indeed, imply an order of that which has parts: but this happens in three ways, as the Philosopher goes on at once to says (Metaph. v, text. 25): namely, "either as to place, or as to power, or as to species." "In saying this," as Simplicius observes in his Commentary on the Predicaments, "he includes all dispositions: bodily dispositions, when he says 'as to place,'" and this belongs to the predicament "Position," which is the order of parts in a place: "when he says 'as to power,' he includes all those dispositions which are in course of formation and not yet arrived at perfect usefulness," such as inchoate science and virtue: "and when he says, 'as to species,' he includes perfect dispositions, which are called habits," such as perfected science and virtue.
982
Objection: 1. It would seem that habit is not a distinct species of quality. Because, as we have said (Article [1]), habit, in so far as it is a quality, is "a disposition whereby that which is disposed is disposed well or ill." But this happens in regard to any quality: for a thing happens to be well or ill disposed in regard also to shape, and in like manner, in regard to heat and cold, and in regard to all such things. Therefore habit is not a distinct species of quality.
2. Further, the Philosopher says in the Book of the Predicaments (Categor. vi), that heat and cold are dispositions or habits, just as sickness and health. Therefore habit or disposition is not distinct from the other species of quality.
3. Further, "difficult to change" is not a difference belonging to the predicament of quality, but rather to movement or passion. Now, no genus should be contracted to a species by a difference of another genus; but "differences should be proper to a genus," as the Philosopher says in Metaph. vii, text. 42. Therefore, since habit is "a quality difficult to change," it seems not to be a distinct species of quality.
On the contrary The Philosopher says in the Book of the Predicaments (Categor. vi) that "one species of quality is habit and disposition."
I answer that The Philosopher in the Book of Predicaments (Categor. vi) reckons disposition and habit as the first species of quality. Now Simplicius, in his Commentary on the Predicaments, explains the difference of these species as follows. He says "that some qualities are natural, and are in their subject in virtue of its nature, and are always there: but some are adventitious, being caused from without, and these can be lost. Now the latter," i.e. those which are adventitious, "are habits and dispositions, differing in the point of being easily or difficultly lost. As to natural qualities, some regard a thing in the point of its being in a state of potentiality; and thus we have the second species of quality: while others regard a thing which is in act; and this either deeply rooted therein or only on its surface. If deeply rooted, we have the third species of quality: if on the surface, we have the fourth species of quality, as shape, and form which is the shape of an animated being." But this distinction of the species of quality seems unsuitable. For there are many shapes, and passion-like qualities, which are not natural but adventitious: and there are also many dispositions which are not adventitious but natural, as health, beauty, and the like. Moreover, it does not suit the order of the species, since that which is the more natural is always first.Therefore we must explain otherwise the distinction of dispositions and habits from other qualities. For quality, properly speaking, implies a certain mode of substance. Now mode, as Augustine says (Gn ad lit. iv, 3), "is that which a measure determines": wherefore it implies a certain determination according to a certain measure. Therefore, just as that in accordance with which the material potentiality [potentia materiae] is determined to its substantial being, is called quality, which is a difference affecting the substance, so that, in accordance with the potentiality of the subject is determined to its accidental being, is called an accidental quality, which is also a kind of difference, as is clear from the Philosopher (Metaph. v, text. 19).Now the mode of determination of the subject to accidental being may be taken in regard to the very nature of the subject, or in regard to action, and passion resulting from its natural principles, which are matter and form; or again in regard to quantity. If we take the mode or determination of the subject in regard to quantity, we shall then have the fourth species of quality. And because quantity, considered in itself, is devoid of movement, and does not imply the notion of good or evil, so it does not concern the fourth species of quality whether a thing be well or ill disposed, nor quickly or slowly transitory.But the mode of determination of the subject, in regard to action or passion, is considered in the second and third species of quality. And therefore in both, we take into account whether a thing be done with ease or difficulty; whether it be transitory or lasting. But in them, we do not consider anything pertaining to the notion of good or evil: because movements and passions have not the aspect of an end, whereas good and evil are said in respect of an end.On the other hand, the mode or determination of the subject, in regard to the nature of the thing, belongs to the first species of quality, which is habit and disposition: for the Philosopher says (Phys. vii, text. 17), when speaking of habits of the soul and of the body, that they are "dispositions of the perfect to the best; and by perfect I mean that which is disposed in accordance with its nature." And since the form itself and the nature of a thing is the end and the cause why a thing is made (Phys. ii, text. 25), therefore in the first species we consider both evil and good, and also changeableness, whether easy or difficult; inasmuch as a certain nature is the end of generation and movement. And so the Philosopher (Metaph. v, text. 25) defines habit, a "disposition whereby someone is disposed, well or ill"; and in Ethic. ii, 4, he says that by "habits we are directed well or ill in reference to the passions." For when the mode is suitable to the thing's nature, it has the aspect of good: and when it is unsuitable, it has the aspect of evil. And since nature is the first object of consideration in anything, for this reason habit is reckoned as the first species of quality.
Reply to Objection: 1. Disposition implies a certain order, as stated above (Article [1], ad 3). Wherefore a man is not said to be disposed by some quality except in relation to something else. And if we add "well or ill," which belongs to the essential notion of habit, we must consider the quality's relation to the nature, which is the end. So in regard to shape, or heat, or cold, a man is not said to be well or ill disposed, except by reason of a relation to the nature of a thing, with regard to its suitability or unsuitability. Consequently even shapes and passion-like qualities, in so far as they are considered to be suitable or unsuitable to the nature of a thing, belong to habits or dispositions: for shape and color, according to their suitability to the nature of thing, concern beauty; while heat and cold, according to their suitability to the nature of a thing, concern health. And in this way heat and cold are put, by the Philosopher, in the first species of quality.
2. Wherefore it is clear how to answer the second objection: though some give another solution, as Simplicius says in his Commentary on the Predicaments.
3. This difference, "difficult to change," does not distinguish habit from the other species of quality, but from disposition. Now disposition may be taken in two ways; in one way, as the genus of habit, for disposition is included in the definition of habit (Metaph. v, text. 25): in another way, according as it is divided against habit. Again, disposition, properly so called, can be divided against habit in two ways: first, as perfect and imperfect within the same species; and thus we call it a disposition, retaining the name of the genus, when it is had imperfectly, so as to be easily lost: whereas we call it a habit, when it is had perfectly, so as not to be lost easily. And thus a disposition becomes a habit, just as a boy becomes a man. Secondly, they may be distinguished as diverse species of the one subaltern genus: so that we call dispositions, those qualities of the first species, which by reason of their very nature are easily lost, because they have changeable causes; e.g. sickness and health: whereas we call habits those qualities which, by reason of their very nature, are not easily changed, in that they have unchangeable causes, e.g. sciences and virtues. And in this sense, disposition does not become habit. The latter explanation seems more in keeping with the intention of Aristotle: for in order to confirm this distinction he adduces the common mode of speaking, according to which, when a quality is, by reason of its nature, easily changeable, and, through some accident, becomes difficultly changeable, then it is called a habit: while the contrary happens in regard to qualities, by reason of their nature, difficultly changeable: for supposing a man to have a science imperfectly, so as to be liable to lose it easily, we say that he is disposed to that science, rather than that he has the science. From this it is clear that the word "habit" implies a certain lastingness: while the word "disposition" does not.Nor does it matter that thus to be easy and difficult to change are specific differences (of a quality), although they belong to passion and movement, and not the genus of quality. For these differences, though apparently accidental to quality, nevertheless designate differences which are proper and essential to quality. In the same way, in the genus of substance we often take accidental instead of substantial differences, in so far as by the former, essential principles are designated.
Summa Th. I-II EN Qu.47 a.4