Summa Theologiae Moralis, vol. I: De Principiis

S. Th. I-II, q. 49; Q. D. de Virt. 1, a. 1.

559. Habit (ἕξις, hexis) is named from the verb to have, whence it signifies a quality or mode by which a thing is disposed in such or such a way in itself or in relation to another. In many ways however something can be disposed; whence the meaning of the word is restricted to indicate only the first species of quality, i.e. the mode by which a thing is disposed in relation to its nature and consequently to its end, and therefore well or ill; namely a perfect and permanent mode which adheres firmly to the thing and therefore is with difficulty lost: thus it is distinguished from a simple disposition which is a mode easily lost by which a thing is disposed in relation to its nature. Habit is therefore a quality difficult to move, according to which the subject is well or ill disposed in itself or in relation to another; — or a stable disposition determining the subject to being well or ill disposed in itself or in relation to operation, in being or in operating.

« Habit, says S. Thomas, C. G. IV, 77, differs from potency in this, that by potency we are able to do something, but by habit we are not rendered able to do something, but fit or unfit for what we are able to do well or ill. By habit therefore there is not given nor taken away from us a certain ability, but this we acquire by habit, that we do something well or ill ».

560. Habit is divided a) into good and evil habit, according as it is a mode agreeing with nature or not agreeing;

b) into substantive or entitative, and operative, according as it is a mode by which nature is well or ill disposed in itself, with respect to being, — or by which it is well or ill disposed in relation to another, with respect to its operation, or by which it is disposed to act suitably or not suitably to its end.

The former immediately inheres in the substance and is principally ordered to being, and not to operating, except mediately inasmuch as being itself is ordered to operating: such are beauty, health, sickness, and sanctifying grace; — the other immediately inheres in an operative potency and therefore is immediately ordered to operation: such are fitness and unfitness, knowledge and art, virtue and vice. « Something is well or ill disposed in two ways: namely in itself or by relation to something. As that which is healthy is well disposed in itself, but that which is robust is well disposed to do something » S. Thom., in V Metaph. lect. 20.

561. Necessity of habits. — That there are operative habits is established by experience: for operations at first very difficult afterward become very easy, as is evident from one who plays the cithara, or dances, or writes, or reads, or studies science, or exercises himself in temperance or drunkenness. — They are necessary in those things which are indifferent: for habit is good or evil; whence nothing has a habit except what can in many and diverse ways be disposed in relation to its nature in itself or to operation. Therefore habits inhere in those things which 1) are in potency, 2) to many, diverse, contrary things, and therefore 3) in many or diverse ways can and ought to be disposed well or ill to their nature or operation. These three conditions are required for this, that something needs a habit. Hence:

1°) There is no habit in God, because in no way is he in potency, but he is his own being and his own operation, and accordingly can be disposed to nothing beyond himself.

2°) Neither is there habit in potencies altogether determined to one thing, because they are sufficient for the act determined and cannot be determined in more ways, nor be more or better or less well disposed; whence the forces of nature do not acquire a habit by their exercise, but always act as much as they can.

3°) But habits are in potencies which are not altogether determined to one thing, and therefore do not have all the propensity which they could have to operation, but to this they can be proportioned in diverse ways. By habit such a potency acquires greater inclination, and so constancy, facility, and pleasure in perfecting its acts. Which mode becomes as it were connatural to it, and therefore it is called habit second nature.

Whence operative habit can be defined: A quality difficult to move by which man is disposed to operating easily, promptly, and delightfully¹; — or a permanent quality superadded to an operative potency and facilitating and inclining it to operating either well or ill, i.e. suitably or not suitably to the end.

562. Observations. — 1°a. From the aforesaid definition it follows:

a) an operative habit is the first (proximate) act of the potency, and the operation is the second act (q. 49, a. 3, ad 1);

b) habit is the mean between pure operative potency (remote first act) and perfect act (operation, second act);

c) habit does not give the potency the ability to operate, but that it operates perfectly, i.e. constantly and uniformly, — promptly, easily, and expeditely, — and delightfully (Q. D. de Virt. 1, a. 1; C. G. IV, 77);

d) an operative habit is truly and properly found in an active potency which properly operates; in a merely passive potency however through which the active operates, it is not found except improperly and secondarily, inasmuch as there is rather a passive quality which this potency easily serves the active potency (q. 50, a. 1).

2°a. An operative habit, while it is in an indifferent potency, does not however completely remove its indifference, nor therefore necessitate it to act; whence S. Thomas says that one uses a habit when one wishes (q. 49, a. 3 sed contra; q. 50, a. 3, ad 2; a. 5).