"The heart cannot remain firm in purity, so as not to be defiled, if it will not be crushed by fasting. It is impossible also to preserve holiness without fasting, and the flesh will not submit to the spirit for spiritual activity, and prayer itself will not rise up and act because natural needs predominate. And the flesh will be compelled to become feverish. And from thoughts the heart is aroused and is defiled, and through this, grace departs, and the unclean spirits have boldness to rule over us as much as they wish." St. Paisius Velichkovsky "Field Flowers"