One of my chief reasons for dividing morality up into three parts was that this seemed the shortest way of covering the ground. Here I want to give some idea of another way in which the subject has been divided by old writers, which was too long to use in my talk, but which is a very good one.
According to this longer scheme there are seven 'virtues'. Four of them are called 'Cardinal' virtues, and the remaining three are called 'Theological' virtues. The 'Cardinal' ones are those which all civilized people recognize: the 'Theological' are those which, as a rule, only Christians know about. I shall deal with the Theological ones later on: at present I am talking about the four Cardinal virtues. (The word 'cardinal' has nothing to do with 'Cardinals' in the Roman Church. It comes from a Latin word meaning 'the hinge of a door'. These were called 'cardinal' virtues because they are, as we should say, 'pivotal'.) They are PRUDENCE, TEMPERANCE, JUSTICE, and FORTITUDE.
Prudence means practical common sense, taking the trouble to think out what you are doing and what is likely to come of it… The proper motto is not 'Be good, sweet maid, and let who can be clever,' but 'Be good, sweet maid, and don't forget that this involves being as clever as you can.' God is no fonder of intellectual slackers than of any other slackers. If you are thinking of becoming a Christian, I warn you, you are embarking on something which is going to take the whole of you, brains and all. But, fortunately, it works the other way round. Anyone who is honestly trying to be a Christian will soon find his intelligence being sharpened: one of the reasons why it needs no special education to be a Christian is that Christianity is an education itself. (Mere Christianity, CS Lewis, 1943)
In C. S. Lewis’ most famous book “Mere Christianity” we find one of the clearest and simplest treatments of the Christian faith. One of the characteristics that makes it so, is the ease with which Lewis interacts with the ancient faith of his own British Isles. A faith that had shaped the whole social mindset of the land for approximately 1800 years by the time of his writing. Therefore, when Lewis speaks of human virtue, he choses to refer to the 7 virtues as taught by the ancient church. Moreover, when referring to the conduct that is befitting all humanity he also refers to what the church calls “The Cardinal Virtues".
The first of these Cardinal virtues is Prudence. The point that he labors in this section stresses the requirement that humanity be involved in thinking deeply about all things, but most importantly about the actions that we take and their affect upon our own and others outer & inner persons. And that is precisely Lewis’ warning. I warn you, you are embarking on something which is going to take the whole of you, brains and all. This sounds entirely too difficult to us who in this present age are continually pointed at the joys of leisure. Following Jesus is not for wimps!