A Fundamental Virtue for the Intellectual Life
The most significant substantive impact on my own intellectual life in the last ten years has come through reading the works of St. Thomas Aquinas. The French philosopher Etienne Gilson wrote an in depth and very fine treatment of Aquinas's thought in The Christian Philosophy of St. Thomas Aquinas. It may be the best introduction to Aquinas available today in English. Gilson is gifted at explaining difficult concepts, but this book is one to be read more than once.
Chapter three of the book is titled "The Personal Life," and it is a short masterpiece on the application of the virtues to reason and the intellectual life in general. Gilson opens the chapter with these words: "The moral life of man consists in the highest development of the potentialities of his nature by acting at all times and in all circumstances under the direction of his reason." Stated differently, by nature (as designed by God), man possesses a number of potentialities that reach fruition to the degree that man acts at all times and in all circumstances under the direction of his reason and not his passions. This is the expression of man's moral life. 
Gilson goes on to note that prudence is "a kind of general moral virtue whose duty it is to guide the other virtues themselves in choosing the means leading to their ends." For example, the virtue of justice has certain ends (goals), and the virtue of prudence guides man in choosing the means best calculated to achieve the ends of justice. Gilson then writes of the life's work of acquiring prudence and states: "[T]his is truly an art. How am I to deal with such and such a man in particular circumstances without humiliating or injuring him? This is the kind of problem which the virtue of prudence places before the understanding."
I would like to think that I always keep in mind the virtue of prudence, but I find myself returning to Gilson and St. Thomas on this issue primarily when I face difficult or complex decisions. I am in one of those periods now, so I naturally thought of Aquinas and turned to him for help. And, I ran across these insightful passages in Gilson and thought of just how fundamental is the virtue of prudence to the intellectual life.
Everything has to be put to work in order to acquire this quality. We must know how to listen, how to follow the advice of those whom knowledge and age have equipped to counsel us. Docility is a part of prudence. But it is not enough to learn from others. We must be prepared to discover on our own how to act in a particular case. This is called address (eustochia, solertia), and is a part of prudence. It is a practical presence of mind. All these qualities demand a well-trained reason, capable of working out the particulars of a problem, of foreseeing the probable consequences of an act, of using powers of circumspection, of weighing the individual circumstances of a situation, of exercising caution lest good intentions ultimately do more harm than good. Reasoning, foresight, circumspection, precaution are all essential elements of prudence, and there is no real prudence without them (Gilson).

















