Tertullian

“ Even if God had enjoined no preceptive fasts, still, by pointing out the source whence Adam was slain, He who had demonstrated the offence had left to my intelligence the remedies for the offence. Unbidden, I would, in such ways and at such times as I might have been able, have habitually accounted food as poison, and taken the antidote, hunger; through which to purge the primordial cause of death—a cause transmitted to me also, concurrently with my very generation ”

“ Further: since He Himself both commands fasting, and calls “a soul [4] wholly shattered”—properly, of course, by straits of diet—“a sacrifice;” who will any longer doubt that of all dietary macerations the rationale has been this, that by a renewed interdiction of food and observation of precept the primordial sin might now be expiated, in order that man may make God satisfaction through the self-same causative material through which he had offended, that is, through interdiction of food ”