Imitation of Christ

Non te reputes aliis meliorem, ne forte coram Deo deterior habearis qui scit quid est in homine. Non superbias de operibus bonis, quia aliter sunt judicia Dei quam hominum, cui sæpe displicet, quod hominibus placet. Si aliquid boni habueris, crede de aliis meliora, ut humilitatem conserves. Non nocet ut te hominibus supponas, nocet autem plurimum, si vel uni te præponas. Jugis pax cum humili, in corde autem superbi zelus et indignatio frequens. 

Count not yourself better than others, lest perchance you appear worse in the sight of God, who knows what is in man. Be not proud of your good works, for God's judgments are of another sort than the judgments of man, and what pleases man is often displeasing to Him. If you have any good, believe that others have more, and so you may preserve your humility. It is no harm to you if you place yourself below all others; but it is great harm if you place yourself above even one. Peace is ever with the humble man, but in the heart of the proud there is envy and continual wrath.

Imitation of Christ, I, 7:3