In February of 1522 Ignatius Loyola was travelling to the shrine of Monserrat when a Moor rode up to him. The two men then rode together. As they were discussing about the Blessed Virgin the Moor said he could not believe she remained a virgin after giving birth to a child. Ignatius insisted she did and as they argued over this point, Ignatius grew increasingly agitated. As their conversation deteriorated the Moor decided to press on ahead, and Ignatius soon lost sight of him. As he reflected on the conversation his temper remained fever pitch to a point he contemplated on finding the Moor and running his sword through the Moor. He struggled with this desire and unable to decide what would be the best course of action. As he approached a fork in the road, the left leading to the town and the right to the Shrine of Monserrat he decided to drop the reins and let his horse decide which direction he should take. If the horse took the road to the town he would seek out the Moor and kill him, otherwise he would spare the Moor.
Later in his autobiography, Ignatius related this story of the Moor, to show how God was influencing his life, while he was still ignorant and blind to the truth, though he was greatly desirous of serving Him in every way he knew how. Notice how he described his intention, “…was greatly desirous of serving Him in every way he knew how.” Even though Ignatius lacked the spiritual maturity at the time, the fact that his desire to serve God as best he knew how was the essential starting point and precondition for the virtue of prudence. His agitation was so great, and his lack of spiritual maturity blinded him from seeing that killing the Moor was less than a Christian response to disparaging of the Blessed Virgin by the Moor. And letting the horse to settle what he should do was not the best way to discern God’s will. But, and here is the point, he nevertheless wanted, profoundly to serve God, and his ignorance and lack of formation didn’t change that.
Now, my relating of this story of Ignatius is actually a preamble to the discussion of the virtue of prudence. There are two types of prudence; natural prudence and moral prudence. Both are desirable, however, natural prudence can be used to serve a bad end, such as to deceive, circumvent, defraud or cheat. In which case the world knows it as calculation or cleverness. By contrast, the virtue of prudence is always directed to doing the will of God. This is why the world may very well judge someone with the virtue of prudence to be lacking in good sense.
Prudence is a kind of built-in priority in relation to the other cardinal virtues. Without prudence, justice can become legalism absent of the spirit of the law, fortitude can become rashness and temperance can become puritanism. But prudence does not rule out mistakes. A prudent man can be wrong. The difference is that the imprudent try to cover up his mistakes while the prudent faces up to his mistake and learns from it.