Early Church Fathers/Monastic thought of the day
“For the mind in prayer is formed by its previous condition, and when we are applying ourselves to prayer the images of the same actions and words and thoughts will dance before our eyes, and make us either angry, as in our previous condition, or gloomy, or recall our former lust and business, or make us shake with foolish laughter (which I am ashamed to speak of) at some silly joke, or smile at some action, or fly back to our previous conversation.
"And therefore if we do not want anything to haunt us while we are praying, we should be careful before our prayer, to exclude it from the shrine of our heart, that we may thus fulfill the Apostle's injunction: "Pray without ceasing;" and: "In every place lifting up holy hands without wrath or disputing."
"For otherwise we shall not be able to carry out that charge unless our mind, purified from all stains of sin, and given over to virtue as to its natural good, feed on the continual contemplation of Almighty God."
Cassian, John. Conferences of John Cassian - Conference 9, Chapter 3.