But on the part of the body, in respect of the individual nature, there are some appetitive habits by way of natural beginnings.  For some are disposed from their own bodily temperament to chastity or meekness or such like.

Reply Obj. 1:  This objection takes nature as divided against reason and will; whereas reason itself and will belong to the nature of man.

Reply Obj. 2:  Something may be added even naturally to the nature of a power, while it cannot belong to the power itself.  For instance, with regard to the angels, it cannot belong to the intellective power itself capable of knowing all things:  for thus it would have to be the act of all things, which belongs to God alone.  Because that by which something is known, must needs be the actual likeness of the thing known:  whence it would follow, if the power of the angel knew all things by itself, that it was the likeness and act of all things.  Wherefore there must needs be added to the angels’ intellective power, some intelligible species, which are likenesses of things understood:  for it is by participation of the Divine wisdom and not by their own essence, that their intellect can be actually those things which they understand.  And so it is clear that not everything belonging to a natural habit can belong to the power.

Reply Obj. 3:  Nature is not equally inclined to cause all the various kinds of habits:  since some can be caused by nature, and some not, as we have said above.  And so it does not follow that because some habits are natural, therefore all are natural. ________________________

SECOND ARTICLE [I-II, Q. 51, Art. 2]

Whether Any Habit Is Caused by Acts?

Objection 1:  It would seem that no habit is caused by acts.  For habit is a quality, as we have said above (Q. 49, A. 1).  Now every quality is caused in a subject, according to the latter’s receptivity.  Since then the agent, inasmuch as it acts, does not receive but rather gives:  it seems impossible for a habit to be caused in an agent by its own acts.

Obj. 2:  Further, the thing wherein a quality is caused is moved to that quality, as may be clearly seen in that which is heated or cooled:  whereas that which produces the act that causes the quality, moves, as may be seen in that which heats or cools.  If therefore habits were caused in anything by its own act, it would follow that the same would be mover and moved, active and passive:  which is impossible, as stated in Physics iii, 8.

Obj. 3:  Further, the effect cannot be more noble than its cause.  But habit is more noble than the act which precedes the habit; as is clear from the fact that the latter produces more noble acts.  Therefore habit cannot be caused by an act which precedes the habit.

On the contrary, The Philosopher (Ethic. ii, 1, 2) teaches that habits of virtue and vice are caused by acts.