"What Lucifer has lost by pride, Mary has gained by humility. What Eve has damned and lost by disobedience, Mary has saved by obedience. Eve, in obeying the serpent, has destroyed all her children together with herself, and has delivered them to him; Mary, being perfectly faithful to God has saved all her children and [...]
"The flatterer is a servant of the devils, a teacher of pride, the destroyer of contrition, a vandal of excellence, a perverse guide. The prophet says this: 'Those who honor you deceive you' (Isa. 3:12)." Source: St. John Climacus, The Ladder of Divine Ascent
"It is impossible without humility to enjoy anything – even pride." Source: G.K. Chesterton, Orthodoxy, Moody Publishers, 2009.
"Like the sun which shines on all alike, vainglory beams on every occupation. What I mean is this. I fast, and turn vainglorious. I stop fasting so that I will draw no attention to myself, and I become vainglorious over my prudence. I dress well or badly, and am vainglorious in either case. I talk [...]
"A proud soul is the slave of cowardice. Trusting only itself, it is frightened by a sound or a shadow." Source: St. John Climacus, The Ladder of Divine Ascent
"There are here two extremes to be avoided: one is to believe that man does everything and God does nothing, which is the Western sin of pride; the other is to believe that God does everything and man does nothing, which is the Oriental sin of fatalism. The golden truth is between the two, as [...]
"Another characteristic of Our Lord's charity is humility. Our Lord looked upon Himself only as the servant of His Apostles. Never put yourself above others. Never esteem yourself more than they on account of your knowledge or virtues. Our Lord treated His Apostles with respect, for charity ought to be respectful... I repeat It, the [...]
"There are two kinds of swords: one that swings outward, and the other, which is thrust inward. One is to harm the neighbor, such as the sword of Peter that hacked off the ear of the high priest’s servant. It was this kind of sword the Divine Master bade be put back into its scabbard. [...]
For what else is pride but, as a saint has defined it, the love of one’s own excellence. Source: St. Bernard of Clairvaux, The Steps of Humility and Pride (Note: This quote was incorrectly attributed to St. Augustine when it was initially posted here.)
"The door to the soul is closed to the entrance of Truth by error, ignorance and prejudice; the door of the heart is closed by pride and unbelief and willful evil, and the door of conscience is barred by the continual habit of evil." Source: Sheen Fulton, Guide to Contentment, Alba House, 2010. [...]