Thomas Aquinas, on Titus 1:15

“All things are clean to the clean: but to them that are defiled, and to unbelievers, nothing is clean: but both their mind and their conscience are defiled.”

“Then when he says, all things are clean to the clean, he specifies the reason behind his statements, namely, how they turn one from the truth and how they repeat fables and commands of men, which are chiefly concerned with distinguishing between foods according to the law, which some false prophets said must be observed. Consequently, first, he shows how these foods are related to those who are good; second, to those who are wicked, at but to them that are defiled. He says, therefore: not giving heed to Jewish fables about food, because all things are clean to the clean. Does this mean that adultery is clean to the clean? I answer: no, because by the very fact that it is adultery it is unclean. But those things that are clean to the clean which of themselves do not defile one. In this matter Matthew says: whatever enters into the mouth does not defile a man (Matt 15:11); therefore, whatever enters the mouth is clean. Against this there are two objections: one is found in Leviticus: and the rock badger, because it chews the cud but does not part the hoof is unclean to you (Lev 11:7). I answer according to Augustine in Against Faustus: a thing is unclean either according to its nature or according to what it signifies; for example, if this word 'fool' is taken merely as a sound, it is not unclean but good; but if it is taken according to its signification, it implies uncleanness, because it signifies lack of wisdom. But the acts of that people were prophetic acts. Hence a pig as such is not unclean, but only inasmuch as it signifies a man given to pleasure. But now that the reality has come, these significations cease, and men use foods according to their nature. Another objection is that in Acts the apostles commanded to abstain from blood and from things strangled (Acts 15:29). Consequently, it does not seem lawful to partake of such things. And so, all things are not clean to the clean. I answer that some believe that this commandment should be interpreted literally, but in a mystical sense, so that by blood is understood homicide, and by strangling, the oppression of the poor. And this is good, but it is not the whole truth. Therefore, I say that literally it is a commandment, but we are not obliged to it. For some things are forbidden because they are evil; and these must simply be avoided. But other things are not evil absolutely, but for a time, and these must be observed so long as a reason exists. But the apostles forbade these things, not because they were evil in themselves, because in Matthew the Lord says the opposite (Matt 15:17). The reason behind them was that some had been converted from Judaism and some from paganism; consequently, it was necessary, if one people was to be formed, that one should condescend to another. In this matter the Jews were to be condescended to, because it was abominable to them to eat blood and anything suffocated. Therefore, to maintain peace, the apostles declared that this law was to be observed for that time. Then when he says, but to them that are defiled, he shows how these foods are regarded by wicked men: concerning this he does three things, first, he shows this; second, he assigns the reason, at but both their mind; third, he manifests this with a sign, at they profess that they know. He says, therefore: those foods are clean to the clean, but unclean to the defiled, i.e., to those whose consciences are defiled: whoever touches pitch will be defiled (Sir 13:1), and to unbelievers, i.e., whose faith is corrupt: he who is an unbeliever, acts unfaithfully (Isa 21:2). Does the unbelieving sinner make an alms unclean? The answer is that the Apostle does not employ an affirmative, but a negative word. Hence he does not say, all; he says that nothing is clean to them, which is true, because nothing is perfectly clean to them, because no act is clean unless it is directed to its proper end; whereas these acts are outside the end. But is anything clean to them? It seems so, although it is also true that whatever does not proceed from faith is sin (Rom 14:23). I answer that evil never corrupts the good altogether. For it is impossible that there not be some good in every sinner, even in devils. Therefore, when a sinner does something precisely as sinner and unbeliever, the entire act is a sin in its root; but if he does something which springs from some good in him, such as from unformed faith or from his nature, it is not unclean. So it is signified that he says, but to them that are defiled and to unbelievers, i.e., in so far as they are such. For they ate contrary to conscience and erred in faith; consequently, what was clean in its very nature they made unclean, as far as they were concerned. The reason for this is that the cause of their acts is unclean, namely, their depraved intellect and will; hence he says, but both their mind and their conscience are defiled, namely, their mind by unbelief, and their conscience by sin: why is it, O Israel, why is it that you are in the land of your enemies, that you are growing old in a foreign country? (Bar 3:10)”

Imported from an open dataset — not yet checked against the printed edition.