The man who has struggled bravely with the passions of the body, has fought ably against unclean spirits, and has expelled from his soul the conceptual images they provoke, should pray for a pure heart to be given him and for a spirit of integrity to be renewed within him (cf. Ps. 51:10). In other words, he should pray that by grace he may be completely emptied of evil thoughts and filled with divine thoughts, so that he may become a spiritual world of God, splendid and vast, wrought from moral, natural and theological forms of contemplation.
Maximus the ConfessorHe who has realized love for God in his heart is tireless in his pursuit of the Lord his God, and bears every hardship, reproach and insult nobly, never thinking the least evil of anyone.
Maximus the ConfessorIt is one thing to be delivered from bad thoughts, and another to be freed from the passions. Often people are delivered from thoughts, when they do not have before their eyes those things which produce passion. But the passions for them remain hidden in the soul, and when the things appear again the passions are revealed. Therefore it is necessary to guard the mind when these things appear, and to know toward which things you have a passion.
Maximus the Confessor