Spiritual work can exist even without bodily labor. Blessed, therefore, is the man who regards spiritual work as superior to physical work: through the first he makes up for any deficiency where the second is concerned, because he lives the hidden life of prayer that is manifest to God.
Strength to pray lies in the deliberate privation of food, and strength to go without food lies in not seeing or hearing about worldly things except when strictly necessary. He who is negligent in this fails to build his fasting on a firm foundation, and so he brings about the collapse of the whole edifice of prayer, which itself is based on fasting.
~Ilias the Presbyter