What Kind of Good Fasting Is

So we must now ask what we ought to hold about fasting. Is it good in the same way as justice, prudence, courage and temperance, which can never become anything else? Or is it something indifferent, which is sometimes useful when done and may sometimes be left undone without condemnation, and which it is sometimes wrong to do and sometimes praiseworthy to leave undone? For if we count fasting among the virtues, so that abstaining from food is placed among the things that are good in themselves, then certainly eating will be bad and wrong. For whatever is the opposite of what is good in its own nature must certainly be held to be bad in its own nature. But the authority of Holy Scripture does not allow us to lay this down. For if we fast with such thoughts and intentions as to think that we fall into sin by taking food, we will not only gain nothing by our abstinence but will actually incur grievous guilt and fall into the sin of impiety, as the apostle says: “Abstaining from foods which God has created to be received with thanksgiving by the faithful and those who know the truth. For every creature of God is good, and nothing is to be refused if it is received with thanksgiving.” For “if a man thinks a thing is unclean, to him it is unclean.” And so we never read that anyone is condemned simply for taking food, but only when something was joined to it or followed after it for which he deserved condemnation. [a]