I answer that, The proper end of each moral virtue consists precisely in conformity with right reason. For temperance intends that man should not stray from reason for the sake of his concupiscences; fortitude, that he should not stray from the right judgment of reason through fear or daring. Moreover this end is appointed to man according to natural reason, since natural reason dictates to each one that he should act according to reason.
But it belongs to the ruling of prudence to decide in what manner and by what means man shall obtain the mean of reason in his deeds. For though the attainment of the mean is the end of a moral virtue, yet this mean is found by the right disposition of these things that are directed to the end.
This suffices for the Reply to the First Objection.
Reply Obj. 2: Just as a natural agent makes form to be in matter, yet does not make that which is essential to the form to belong to it, so too, prudence appoints the mean in passions and operations, and yet does not make the searching of the mean to belong to virtue.
Reply Obj. 3: Moral virtue after the manner of nature intends to attain the mean. Since, however, the mean as such is not found in all matters after the same manner, it follows that the inclination of nature which ever works in the same manner, does not suffice for this purpose, and so the ruling of prudence is required. _______________________
EIGHTH ARTICLE [II-II, Q. 47, Art. 8]
Whether Command Is the Chief Act of Prudence?
Objection 1: It would seem that command is not the chief act of prudence. For command regards the good to be ensued. Now Augustine (De Trin. xiv, 9) states that it is an act of prudence "to avoid ambushes." Therefore command is not the chief act of prudence.
Obj. 2: Further, the Philosopher says (Ethic. vi, 5) that "the prudent man takes good counsel." Now "to take counsel" and "to command" seem to be different acts, as appears from what has been said above (I-II, Q. 57, A. 6). Therefore command is not the chief act of prudence.
Obj. 3: Further, it seems to belong to the will to command and to rule, since the will has the end for its object, and moves the other powers of the soul. Now prudence is not in the will, but in the reason. Therefore command is not an act of prudence.