"A person who suffers bitterly when slighted or insulted should recognize from this that he still harbours the ancient serpent in his breast. If he quietly endures the insult or responds with great humility, he weakens the serpent and lessens its hold. But if he replies acrimoniously or brazenly, he gives it the strength to pour its venom into his heart and to feed mercilessly on his guts. In this way the serpent becomes increasingly powerful; it destroys his soul's strength and his attempts to set himself right, compelling him to live for sin and to be completely dead to righteousness."
St. Symeon the New Theologian - One Hundred and Fifty-Three Practical and Theological Texts - The Philokalia