Is the natural law a habit [of the soul]?

It seems that the natural law is a habit [of the soul]:

Objection 1:  As the Philosopher says in Ethics 2, “There are three sorts of things in the soul:  powers, habits, and passions.”  But as is clear from going through each of these one by one, the natural law is not one of the powers of the soul or one of the passions.  Therefore, the natural law is a habit.

Objection 2:  Basil says, “Conscience (conscientia) or synderesis (synderesis) is our intellect’s law”—and by this he cannot mean anything other than the natural law.  But as was established in the First Part (ST 1, q. 79, a. 12), synderesis is a certain habit.  Therefore, the natural law is a habit.

Objection 3:  As will be shown below (a. 6), the natural law remains within a man always.  But a man’s reason, which is what the law has to do with, is not always actually thinking about the natural law.  Therefore, the natural law is a habit and not an act.

But contrary to this:  In De Bono Coniugali Augustine says, “A habit is that by means of which something is done when there is need.”  But the natural law is not like this, since it exists even in children and in the damned, who cannot act through it.  Therefore, the natural law is not a habit.

I respond:  There are two senses in which something can be called a habit.
In the first sense, something is called a habit properly and essentially, and in this sense the natural law is not a habit.  For it was explained above (q. 90, a. 1) that the natural law is something constituted by reason, in the same way that a proposition is a work of reason.  But what someone does or makes is not the same as that by means of which he does it or makes it.  For instance, it is by means of the habit of grammar that someone makes a coherent utterance.  Therefore, since a habit is that by means of which one acts, no sort of law can be a habit properly and essentially.
In the second sense, that which is had by means of a habit can itself be called the habit—in the way that the Faith is that which is held by means of faith.  And since the precepts of the natural law are such that even though at times they are actually being considered by reason, at other times they exist only habitually in reason, one can say in this sense that the natural law is a habit.  In the same way, the indemonstrable principles in speculative matters are not the habit itself with respect to the principles; rather, they are principles with respect to which there is a habit.

Reply to objection 1:  In this passage the Philosopher means to be looking for the genus of virtue, and since it is clear that a virtue is a principle of acts, he proposes only the sorts of things that serve as the principles of human acts, viz., powers, habits, and passions.  However, besides these three, there are other sorts of things that exist in the soul.  For instance, certain kinds of acts exist in the soul, e.g., an act of willing exists in one who wills; (b) again, things that are known exist in the one who knows them; and (c) the natural properties of the soul exist in the soul, e.g., immortality and others of this sort.

Reply to objection 2:  Synderesis is called our intellect’s law because it is a habit containing the precepts of the natural law, which are first principles of human works.

Reply to objection 3:  The conclusion of this argument is that the natural law is had in a habitual manner. This we concede.

Reply to argument for the contrary:  By the very fact that something exists habitually in a man, he is sometimes be unable to make use of it because of an impediment.  For instance, a man who is sleeping cannot make use of his habit of grasping [first] principles (intellectus).  In the same way, a young child cannot make use of the habit of grasping [first] principles or, again, make use of the natural law, which exists in him habitually, because he is not the right age.