'Mere Christianity,' bk 3, ch. 8

"There is one vice of which no man in the world is free; which every one in the world loathes when they see it in someone else; and of which hardly any people, except Christians, ever imagine that they are guilty themselves....
    The essential vice, the utmost evil, is Pride.  Unchastity, anger, greed, drunkenness, and all that, are mere fleabites in comparison: 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....
    If I am a proud man, then, as long as there is one man in the whole world more powerful, or richer, or cleverer than I, he is my rival and my enemy....
    As long as you are proud you cannot know God. A proud man is always looking down on things and people: and, of course, as long as you are looking down, you cannot see something that is above you....
    The real test of being in the presence of God is that you either forget about yourself altogether or see yourself as a small, dirty object.  It is better to forget about yourself altogether....
    The other, and less bad, vices come from the devil working on us through out animal nature. But [Pride] does not come through our animal nature at all. It comes direct from Hell. It is purely spiritual: consequently it is far more subtle and deadly.  For the same reason, Pride can often be used to beat down the simpler vices. Teachers, in fact, often appeal to a boy's pride, or, as they call it, his self-respect, to make him behave decently: many a man has overcome cowardice, or lust, or ill-temper by learning to think that they are beneath his dignity -- that is, by Pride. The devil laughs. He is perfectly content to see you becoming chaste and brave and self-controlled provided, all the time, he is setting up in you the Dictatorship of Pride -- just as he would be quite content to see your chilbains cured if he was allowed, in return, to give you cancer. for Pride is spiritual cancer: it eats up the very possibility of love, or contentment, or even common sense." -- Mere Christianity, bk 3, ch. 8