Humans are amphibians - half spirit and half animal. As spirits they belong to the eternal world, but as animals they inhabit time.
C. S. LewisNow we cannot...discover our failure to keep God's law except by trying our very hardest (and then failing). Unless we really try, whatever we say there will always be at the back of our minds the idea that if we try harder next time we shall succeed in being completely good. Thus, in one sense, the road back to God is a road of moral effort, of trying harder and harder. But in another sense it is not trying that is ever going tobring us home. All this trying leads up to the vital moment at which you turn to God and say, "You must do this. I can't.
C. S. LewisThe vice I am talking of is Pride or Self-Conceit: and the virtue opposite to it, in Christian morals, is called Humility...According to Christian teachers, the essential vice, the utmost evil, is Pride. Unchastity, anger, greed, drunkenness, and all that, are mere flea bites 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.
C. S. Lewis