Reply Obj. 3:  In angels there are no essential parts:  but there are potential parts, in so far as their intellect is perfected by several species, and in so far as their will has a relation to several things. ________________________

QUESTION 51

OF THE CAUSE OF HABITS, AS TO THEIR FORMATION
(In Four Articles)

We must next consider the cause of habits:  and firstly, as to their formation; secondly, as to their increase; thirdly, as to their diminution and corruption.  Under the first head there are four points of inquiry: 

(1) Whether any habit is from nature?

(2) Whether any habit is caused by acts?

(3) Whether any habit can be caused by one act?

(4) Whether any habits are infused in man by God?
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FIRST ARTICLE [I-II, Q. 51, Art. 1]

Whether Any Habit Is from Nature?

Objection 1:  It would seem that no habit is from nature.  For the use of those things which are from nature does not depend on the will.  But habit “is that which we use when we will,” as the Commentator says on De Anima iii.  Therefore habit is not from nature.

Obj. 2:  Further, nature does not employ two where one is sufficient.  But the powers of the soul are from nature.  If therefore the habits of the powers were from nature, habit and power would be one.

Obj. 3:  Further, nature does not fail in necessaries.  But habits are necessary in order to act well, as we have stated above (Q. 49, A. 4).  If therefore any habits were from nature, it seems that nature would not fail to cause all necessary habits:  but this is clearly false.  Therefore habits are not from nature.

On the contrary, In Ethic. vi, 6, among other habits, place is given to understanding of first principles, which habit is from nature:  wherefore also first principles are said to be known naturally.

I answer that, One thing can be natural to another in two ways.  First in respect of the specific nature, as the faculty of laughing is natural to man, and it is natural to fire to have an upward tendency.  Secondly, in respect of the individual nature, as it is natural to Socrates or Plato to be prone to sickness or inclined to health, in accordance with their respective temperaments.  Again, in respect of both natures, something may be called natural in two ways:  first, because it entirely is from the nature; secondly, because it is partly from nature, and partly from an extrinsic principle.  For instance, when a man is healed by himself, his health is entirely from nature; but when a man is healed by means of medicine, health is partly from nature, partly from an extrinsic principle.