Prudence means practical common sense, taking the trouble to think out what you are doing and what is likely to come of it. — C. S. Lewis 
Prudence is important, though often overlooked because it usually goes unnoticed until it is absent. Prudence is one of the four “the Cardinal Virtues” (the others are courage, temperance, and justice). These virtues were recognized by both the ancient philosophers and the (slightly less ancient) early church theologians who added the theological virtues of faith, hope, and love.
 C. S. Lewis, “The Cardinal Views,” in Mere Christianity (1952).