Rom 14:5

“According to the spiritual interpretation, which we have already expounded in the case of food, the word day is used to mean a portion of holy Scripture in which the doctrine of godliness and faith is contained. For it is the day which enlightens the mind, which drives away the darkness of ignorance. The day has Christ, the sun of righteousness, in it. If one person dedicates himself to the study of holy Scripture and discovers the true meaning of every day, so that not one jot or tittle of the law escapes him, then it can be said that he "esteems all days alike." Another person may not have reached that point but still has enough to be able to understand the basic tenets of the faith. Therefore both are to give thanks to God, according to the apostle's teaching. One understands and enjoys everything, whereas another does not understand everything but will nevertheless be saved by confessing the little that he does know.”

“"One man esteemeth one day above another, another esteemeth every day alike." Here he seems to me to be giving a gentle hint about fasting. For it is not unlikely that some who fasted were always judging those who did not, or among the observances it is likely that there were some that on fixed days abstained, and on fixed days did not. Whence also he says, "Let every man be fully persuaded in his own mind." And in this way he released those who kept the observances from fear, by saying that the thing was indifferent, and he removed also the quarrelsomeness of those who attacked them, by showing that it was no very desirable task to be always making a trouble about these things. Yet it was not a very desirable task, not in its own nature, but on account of the time chosen, and because they were novices in the faith. For when he is writing to the Colossians, it is with great earnestness that he forbids it, saying, "Beware lest any man spoil you through philosophy and vain deceit, after the traditions of men, after the elements of the world, and not after Christ." (Col. ii. 8.) And again, "Let no man judge you in meat or in drink" (Col. ii. 16), and, "let no man beguile you of your reward." (Col. ii. 18.) And when writing to the Galatians with great precision, he exacts of them Christian spirit and perfectness in this matter. But here he does not use this vehemency, because the faith was lately planted in them. Let us therefore not apply the phrase, "Let every man be persuaded in his own mind," to all subjects. For when he is speaking of doctrines, hear what he says, "If any one preacheth unto you any gospel other than that ye have received, let him be accursed" (Gal. i. 9), "even" if it be "an angel." And again, "I fear lest by any means as the serpent beguiled Eve through his subtilty, so your minds should be corrupted." (2 Cor. xi. 3.) And in writing to the Philippians, he says, "Beware of dogs, beware of evil workers, beware of the concision." (Phil. iii. 2.) But with the Romans, since it was not yet the proper time for setting things of this sort right, "Let every man," he says, "be fully persuaded in his own mind." For he had been speaking of fasting.”

“Therefore Paul is speaking here about fasting and abstinence, which are not treated under a fixed provision of the law. Each individual should do whatever he sees fit in the light of his desire to share in the reward. Thus it follows that in a matter of this kind one should simply do what he himself has judged to be better.”

“At the moment, and without any deeper consideration, it seems to me that this is said about God and man, not about two men. He who judges on alternate days is man, who can judge one way today and another way tomorrow.… But the One whose judgment is the same every day is the Lord.… But let everyone dare to judge only insofar as is granted to human intelligence or at least to his own.”

“Some exhausted themselves by not eating or abstained from pork on certain days, while others always ate food and condemned those who fasted. About these he says that one judges one way and another differently, whereas the matter here is indifferent. Therefore one must not attack the brethren on account of this. In this he makes allowance for those being rebuked, because they were still new in the faith. When it comes to dogmas, we must not act according to the assurance of our own mind, but must firmly hold to what we have received, even if an angel from heaven should preach to us something different. But here the subject is food and fasts and the like, and those who stumble over these things are still new in the faith and in need of condescension, and therefore it was necessary to grant them some relaxation with regard to a life ordered in all strictness.”

“Then when he says, for one judges, he exemplifies what he had said. First, he proposes that human opinions vary, saying: I say that to his own lord he stands or falls . . . for one judges between day and day, i.e., he judges between one day and another, so that he abstains on one day and not on another. This seems to refer to those weak in faith, who suppose that the practices of the law must still be observed. For it says in Leviticus: on the tenth day of this seventh month is the day of atonement; and you shall afflict yourselves on this day (Lev 23:27). And in Judith it is stated that Judith fasted all the days of her life, except on Sabbaths, new moons, and feasts of the house of Israel (Jdt 8:6). And another judges every day alike as far as observing the practices of the law, because these had now ceased. Hence this seems to refer to the perfect in faith: bless his name from day to day (Ps 96:2). This can also refer to cases of abstaining performed to control sensual desires. Some abstain in this manner every day; for example, those who always abstain from meat or wine or fast, although some abstain on certain days and not on others: for everything there is a season (Eccl 3:1). Second, he shows that all these things can pertain to the glory of God, saying: let every man abound in his own sense, i.e., be left to his own judgment: God made man from the beginning and left him in the hand of his own counsel (Sir 15:14). Or in his own sense, i.e., according to his own mind let him be zealous to abound to the glory of God, according to 1 Corinthians: seek to abound unto the edifying of the Church (1 Cor 14:12). But this seems to apply to things that are not of themselves evil. In things that are of themselves evil, however, man must not be left to follow his own mind. But that a person discriminates between days seems to be evil of itself according to the first explanation. For it says in Galatians: you observe days and months and seasons and years! I fear that I have labored over you in vain (Gal 4:10). And he is speaking there about those who claimed that days must be observed according to the ceremonies of the law. The answer is that the Apostle is speaking here in regard to that time in which it was lawful for Jews converted to the faith to observe the practices of the law. But in regard to the second explanation it seems to be illicit for him to say: and another judges every day. For there are some days on which it is unlawful to fast. For Augustine says in his Letter to Casulanus: whoever thinks that a fast should be decreed on the Lord's day would not be a small scandal to the Church, and rightfully so. For on those days about which the Church or Sacred Scripture has decreed nothing definite, the customs of the people of God and the decrees of the major authorities must be considered the law. And in the Decretals it is written (Decretal 30): if on account of a public penance received from a priest a presbyter were to fast without any other need on the Lord's day, let him be anathema. But one should understand that the Apostle is speaking here about those abstinences that can be licitly undertaken on any day without clashing with the common custom, or with the customs established by those in authority.”