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 civilised people recognise: 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....
There is a difference between doing some particular just or temperate action and being a just or temperate man. Someone who is not a good tennis player may now and then make a good shot. What you mean by a good player is a man whose eye and muscles and nerves have been so trained by making innumerable good shots that they can now be relied on. They have a certain tone or quality which is there even when he is not playing, just as a mathematician’s mind has a certain habit and outlook which is there even when he is not doing mathematics. In the same way a man who perseveres in doing just actions gets in the end a certain quality of character. Now it is that quality rather than the particular actions which we mean when we talk of a ‘virtue’.
Quotes from Mere Christianity, Part 35
C.S. Lewis, Mere Christianity (1952; Harper Collins 2001) 76, 79-80.