It is helpful to consider prudence as wisdom with respect to time because knowing what to do is often straightforward enough, but when to do it is complex. The Greeks had two words for time: chronos and kairos. Chronos is time as experienced in an ordinary, linear way. Kairos is time experienced as an opportunity. One would ask, "What is the chronos (time)?" But declare, "Now is the kairos (time) to act!"
In order to make decisions in the present, prudence looks ahead into the future and, at the same time, analyzes the past. In fact, the word prudence in Latin is a contracted form of the word "foresight." Independently preceding Latin ideas of prudence, the Proverbs of Solomon say, "A prudent man foresees evil, and hides himself: but the simple pass on, and are punished" (Prov. 22:3).
Prudence gives reason and direction to the other virtues. Aquinas called prudence the auriga virtutum (charioteer of the virtues). He writes, "Prudence is the mover of all the other virtues...and consequently each moral virtue...has something of the movement of prudence" (Summa Question 2 Article 4). Prudence, or accurate reasoning that leads to correct action, directs temperance, courage, and justice. For example, Prudence keeps courage from rashness. Prudence holds moderation in moderation. Prudence does not allow justice to be overly harsh, or mercy to be weakness.
Furthermore, prudence brings us away from binary decisions. Sometimes it is helpful to think of life in black and white, right and wrong, narrow way and broad path. Some of the cardinal virtues work very well in this scheme. Temperance tells us "Avoid the temptation!" and Courage tells us, "Act, now!" However, we can also use metaphors to describe life that capture its complexity. We may find ourselves having to navigate a labyrinth or walk in a shadowed forest, lost. Prudence is the guide through these difficult situations.
The ability to make prudent decisions is often associated with experience. Cicero said that "prudence belongs to old age." However, experience only produces wisdom if the experience is used well. I think the most startling, and certainly the most tragic, example of the "old fool" in literature is King Lear. Lear, at the wane of his regal powers and wishing to have a comfortable slide into retirement gives his kingdom to his daughters. King Lear has three daughters. The two evil daughters flatter him and gain the kingdom. The one who loves him, Cordelia, refuses to flatter him and is banished. Events proceed rapidly downhill from there! Age brings prudence only to the person who is and has been pursuing prudence.
But where do we gain the wisdom of knowing when and how to act? Plato's dialogue Meno touches on a theory of where virtue is found. In the course of the dialogue, Socrates, in typical fashion, leaves his conversation partner flustered as to what he thought the source of wisdom was. Then Socrates proceeds, through questions, to build a case that virtue is not to be found innately in humans. Nor can it be taught like a craft or area of knowledge, like soldiering, painting, or public speaking. At the end of the dialogue, he concludes, as always, by leaving the question more or less open: "...If we [have been] right...virtue would be neither an inborn quality nor taught, but comes to those who possess it as a gift from the gods..."1 This is, in fact, the constant refrain of Socrates. The beginning of wisdom is knowing that one is not innately wise.
This realization is how King Solomon, the wisest man, gained his wisdom seven hundred years before Socrates lived. God came to him in a dream and offered him riches, long life, and power. Solomon, however, overwhelmed with the task of ruling a nation, asks for wisdom. God granted him this along with all the other gifts. And so, Solomon begins his book of Proverbs, "The fear of the Lord is the beginning of wisdom." What this story shows is that wisdom begins with the understanding that we are not wise, but that if we search for wisdom from the source of wisdom, it may be revealed to us.
Let's bring the conversation back to the idea of time as kairos. Prudence knows the kairos in which to act. As we have seen, the best place to start in knowing how to wisely act in time and with time, is an acceptance that we may not know. The next step is to prudently consider the past and future. Where am I headed on this current path? Is there a past example that informs my present decision? What season of life am I in now, and what comes ahead? Questions like these seem obvious, and yet how often do we really take a full and honest assessment of our lives?
I think Solomon said it well in Ecclesiastes 3:
"To everything there is a season, and a time to every purpose under the heaven: a time to be born and a time to die; a time to plant, and a time to pluck up that which is planted; a time to kill and a time to heal; a time to break down and a time to build up; a time to weep and a time to laugh; a time to mourn and a time to dance; a time to cast away stones and a time to gather stones together; a time to embrace and a time to refrain from embracing; a time to get and a time to lose; a time to keep and a time to cast away; a time to rend and a time to sew; a time to keep silence and a time to speak; a time to love and a time to hate; a time of war and a time of peace."
Knowing what the kairos is takes prudence.