There is an intimate connection between the virtue of prudence and the other cardinal virtues, known as the moral virtues. Essentially, one who practices moral virtue moves toward the Good habitually. In order to move toward the Good, you must both desire it and determine how to achieve it by particular acts. The latter requires prudence, for "it belongs to prudence...to apply right reason to action." (S.T.II-II.47.44.c) But without the moral virtues, the practical intellect is swayed and blinded by vicious desires and does not rightly perceive it's End. St. Thomas summarizes the connection: "No moral virtue can be without prudence; since it is proper to moral virtue to make a right choice...Now right choice requires not only the inclination to a due end, which inclination is the direct outcome of moral virtue, but also correct choice of things conducive to the end, which choice is made by prudence...In like manner one cannot have prudence unless one has the moral virtues: since prudence is 'right reason about things to be done,' and the starting point of reason is the end of the thing to be done, to which end man is rightly disposed by moral virtue." (S.T. I-II.65.1.c) Thus, you only possess the moral virtues to the degree that you possess prudence and you only possess prudence to the degree that you possess the moral virtues (a kind of "virtuous circle"... LOL).
[Please note, a man may by nature or habit possess the inclination to one or another form of good deed, thus appearing to possess one virtue without the others. However, such a man possesses the virtue imperfectly, for "the perfect moral virtue is a habit that inclines [one] to do a good deed well."(S.T. I-II.65.1.c) For example, you do not practice obedience, a part of justice, well unless you practice it with discretion, which is a part of prudence.]
To return to my original point, prudence is necessary for the practice of the moral virtues, but one cannot acquire prudence without practicing docility. According to St. Thomas: "Prudence is concerned with particular matters of action, and since such matters are of infinite variety, no one man can consider them all sufficiently; nor can this be done quickly, for it requires length of time. Hence in matters of prudence man stands in very great need of being taught by others, especially by old folk who have acquired a sane understanding of the ends in practical matters. ...Now it is a mark of docility to be ready to be taught: and consequently docility is fittingly reckoned a part of prudence." (S.T. II-II.49.3.c) In short, a man's knowledge is limited by his material nature. Earthly life is temporal, but man learns gradually through the senses and the human intellect can only grasp so much. However, prudence depends upon knowledge. So, in order to achieve prudence we must be receptive to the wisdom of others. We call this receptivity, docility.
Docility is not a virtue honored by the modern world. The Enlightenment cast off authority, advocating intellectual freedom and equality. A few centuries later, those notions still profoundly influence American culture. According to St. Thomas, freedom is "the capacity to choose wisely and to act well as a matter of habit." The object of the will is happiness, the possession of the Good, and when the will is truly free it can pursue its object unhindered by any error of judgment or misplaced desire. However, the freedom idolized by American culture is a freedom outside the boundaries of an objective human good; it is, rather, a freedom to determine one's own good. Although, in principle, many recognize the absurdity of moral relativity, the atmosphere of intellectual independence and skepticism lingers. But the practice of docility requires something else. It requires that we weigh our opinions carefully, timidly against the conclusions of age, wisdom, tradition, or other figures of authority. Infallible dogma set aside, this does not imply a blind submission to authority. Rather, one should give the benefit of the doubt to authority; if you cannot understand or make sense of its claims, assume first that the lack is in you.