We know indeed, dearly-beloved, your devotion to be so warm that in the fasting, which is the forerunner of the Lord's Easter, many of you will have forestalled our exhortations. But because the right practice of abstinence is needful not only to the mortification of the flesh but also to the purification of the mind, we desire your observance to be so complete that, as you cut down the pleasures that belong to the lusts of the flesh, so you should banish the errors that proceed from the imaginations of the heart. For he whose heart is polluted with no misbelief prepares himself with true and reasonable purification for the Paschal Feast, in which all the mysteries of our religion meet together....For the mind then only keeps holy and spiritual fast when it rejects the food of error and the poison of falsehood, which our crafty and wily foe plies us with more treacherously now, when by the very return of the venerable Festival, the whole church generally is admonished to understand the mysteries of its salvation.
St. Leo I, Sermon 46.1
