“So come to your senses and expel those words from your nous. Even if a humble person falls ten thousand times, he will rise once again, and his fall is reckoned as a victory. But as soon as a proud person falls into sin, he also falls into despair and his heart hardens, and then he no longer wants to rise. Despair is a mortal sin, and the devil rejoices in it more than anything. But it disperses immediately through confession.”

Monastic Wisdom: The Letters of Elder Joseph the Hesychast