C.S. Lewis on Pride from his book Mere Christianity:
"I now come to that part of Christian morals where they differ most from all other morals. There is one vice of which no man in the world is free; which every one in the world loathes when he sees it in someone else; and of which hardly any people, except Christians, ever imagine that they are guilty themselves...the more we have it ourselves, the more we dislike it in others.
The vice I am talking of is Pride or Self-Conceit: and the virtue opposite it, in Christian morals, is called Humility...According to Christian teachers, the essential vice, the utmost evil is Pride...it was through Pride that the devil became the devil: Pride leads to every other vice: it is the complete anti-God state of mind...
...pride always means enmity—it is enmity. And not only enmity between man and man, but enmity to God.
In God you come up against something which is in every respect immeasurably superior to yourself. Unless you know God as that--and, therefore, know yourself as nothing in comparison—you do not know God at all. As long as you are proud you cannot know God. A proud man is looking down on things and people: and, of course, as long as you are looking down, you cannot see something that is above you...
...Do not imagine that if you meet a really humble man he will be what most people call humble nowadays: he will not be a sort of greasy, smarmy person, who is always telling you that, of course, he is nobody. Probably all you will think about him is that he seemed a cheerful, intelligent chap who took a real interest in what you said to him. If you do dislike him it will be because you feel a little envious of anyone who seems to enjoy life so easily. He will not be thinking about humility: he will not be thinking about himself at all.
If anyone would like to acquire humility, I can, I think, tell him the first step. The first step is to realize that one is proud. And a biggish step too. At least, nothing whatever can be done before it. If you think you are not conceited, it means you are very conceited indeed."