“Do you think that I posit the antiquity of fasting on the basis of the law? Indeed, fasting is older than the law. …Fasting is as old as humanity: it was legislated in paradise. It was the first command that Adam received: You shall not eat from the tree of the knowledge of good and evil. You shall not eat legislates fasting and self-control. …It is because we did not fast that we were banished from paradise. So let us fast that we may return to it.”

-St. Basil the Great, “First Homily on Fasting,” On Feasting and Fasting.