One who is repentant cannot be haughty...
("Philokalia (Vol. 1)", p. 134, text 110)
Just as water and fire cannot be combined, so self-justification and humility exclude one another.
("Philokalia (Vol. 1)", p. 119, text 125)
Censure from men afflicts the heart; but if patiently accepted it generates purity.
("Philokalia (Vol. 1)", p. 113, text 49)
When you have done something good, remember the words "without Me you can do nothing." (John 15:5).
("Philokalia (Vol. 1)", p. 113, text 41)
Humility is hard to acquire, and the deeper it is, the greater the struggle needed to gain it. There are two different ways in which it comes to those who share in divine knowledge. In the case of one who has advanced halfway along the path of spiritual experience, his self-will is humbled either by bodily weakness, or by people gratuitously hostile to those pursuing righteousness, or by evil thoughts. But when the intellect fully and consciously senses the illumination of God's grace, the soul possesses a humility which is, as it were, natural... The first type of humility is usually marked by remorse and despondency, the second by joy and an enlightened reverence... That is why the first is often undermined by material prosperity, while the second, even if offered all the kingdoms of this world, is not elated and is proof against the arrows of sin. Being wholly spiritual, it is completely indifferent to all material glory. We cannot acquire the second without having passed through the first; for unless God's grace begins by softening our will by means of the first, testing it through assaults of the passions, we cannot receive the riches of the second.
("Philokalia (Vol. 1)", pp. 292-293, text 95)