ey are ordained. Now a habit is a disposition
implying a twofold order: viz. to nature and to an operation
consequent to nature.

Accordingly habits are specifically distinct in respect of three
things. First, in respect of the active principles of such
dispositions; secondly, in respect of nature; thirdly, in respect of
specifically different objects, as will appear from what follows.

Reply Obj. 1: In distinguishing powers, or also habits, we must
consider the object not in its material but in its formal aspect,
which may differ in species or even in genus. And though the
distinction between specific contraries is a real distinction yet
they are both known under one aspect, since one is known through the
other. And consequently in so far as they concur in the one aspect of
cognoscibility, they belong to one cognitive habit.

Reply Obj. 2: The physicist proves the earth to be round by one
means, the astronomer by another: for the latter proves this by means
of mathematics, e.g. by the shapes of eclipses, or something of the
sort; while the former proves it by means of physics, e.g. by the
movement of heavy bodies towards the center, and so forth. Now the
whole force of a demonstration, which is "a syllogism producing
science," as stated in Poster. i, text. 5, depends on the mean. And
consequently various means are as so many active principles, in
respect of which the habits of science are distinguished.

Reply Obj. 3: As the Philosopher says (Phys. ii, text. 89; Ethic.
vii, 8), the end is, in practical matters, what the principle is in
speculative matters. Consequently diversity of ends demands a
diversity of virtues, even as diversity of active principles does.
Moreover the ends are objects of the internal acts, with which, above
all, the virtues are concerned, as is evident from what has been said
(Q. 18, A. 6; Q. 19, A. 2, ad 1; Q. 34, A. 4).
________________________

THIRD ARTICLE [I-II, Q. 54, Art. 3]

Whether Habits Are Divided into Good and Bad?

Objection 1: It would seem that habits are not divided into good and
bad. For good and bad are contraries. Now the same habit regards
contraries, as was stated above (A. 2, Obj. 1). Therefore habits are
not divided into good and bad.

Obj. 2: Further, good is convertible with being; so that, since it is
common to all, it cannot be accounted a specific difference, as the
Philosopher declares (Topic. iv). Again, evil, since it is a
privation and a non-being, ca