Thomas Aquinas

“ And everyone is bound by the natural dictate of reason to practice fasting as far as it is necessary for these purposes. Wherefore fasting in general is a matter of precept of the natural law, while the fixing of the time and manner of fasting as becoming and profitable to the Christian people, is a matter of precept of positive law established by ecclesiastical authority: the latter is the Church fast, the former is the fast prescribed by nature. ”

“ I answer that, Habit and act have the same matter. Wherefore every virtuous act about some particular matter belongs to the virtue that appoints the mean in that matter. Now fasting is concerned with food, wherein the mean is appointed by abstinence. Wherefore it is evident that fasting is an act of abstinence. ”

“ Those commandments which are given under the form of a general precept, do not bind all persons in the same way, but subject to the requirements of the end intended by the lawgiver. It will be a mortal sin to disobey a commandment through contempt of the lawgiver's authority, or to disobey it in such a way as to frustrate the end intended by him: but it is not a mortal sin if one fails to keep a commandment, when there is a reasonable motive, and especially if the lawgiver would not insist on its observance if he were present. ”

“ The fast of the Church is another kind and is called the "fasting of the faster," and this is not broken save by such things as the Church intended to forbid in instituting the fast. Now the Church does not intend to command abstinence from drink, for this is taken more for bodily refreshment, and digestion of the food consumed, although it nourishes somewhat. It is, however, possible to sin and lose the merit of fasting, by partaking of too much drink: as also by eating immoderately at one meal. ”

“ Yet reason does not retrench so much from one's food as to refuse nature its necessary support: thus Jerome says:* "It matters not whether thou art a long or a short time in destroying thyself, since to afflict the body immoderately, whether by excessive lack of nourishment, or by eating or sleeping too little, is to offer a sacrifice of stolen goods." ”

“ Wherefore in making such precepts the lawgiver considers what happens generally and for the most part, and he does not intend the precept to be binding on a person in whom for some special reason there is something incompatible with observance of the precept. Yet discretion must be brought to bear on the point. For if the reason be evident, it is lawful for a man to use his own judgment in omitting to fulfil the precept, especially if custom be in his favor, or if it be difficult for him to have recourse to superior authority. ”

“ We may also reply that even properly speaking fasting is abstinence from all manner of lust, since, as stated above (A [1] , ad 1) , an act ceases to be virtuous by the conjunction of any vice.
Reply to Objection 2: Nothing prevents the act of one virtue belonging to another virtue, in so far as it is directed to the end of that virtue, as explained above (Q [32] , A [1] , ad 2; Q [85] , A [3] ) . Accordingly there is no reason why fasting should not be an act of religion, or of chastity, or of any other virtue. ”

“ It belongs to fortitude as a special virtue, to endure, not any kind of hardship, but only those connected with the danger of death. To endure hardships resulting from privation of pleasure of touch, belongs to temperance and its parts: and such are the hardships of fasting. ”

“ But if one be under the necessity of starting on the pilgrimage at once, and of making long stages, or of doing much work, either for one's bodily livelihood, or for some need of the spiritual life, and it be impossible at the same time to keep the fasts of the Church, one is not bound to fast: because in ordering fasts the Church would not seem to have intended to prevent other pious and more necessary undertakings. ”

“ Such are the flesh of animals that take their rest on the earth, and of those that breathe the air and their products, such as milk from those that walk on the earth, and eggs from birds. For, since such like animals are more like man in body, they afford greater pleasure as food, and greater nourishment to the human body, so that from their consumption there results a greater surplus available for seminal matter, which when abundant becomes a great incentive to lust. Hence the Church has bidden those who fast to abstain especially from these foods. ”

“ Wherefore the fixing of such a time cannot do much harm to anyone, whatever his circumstances may be. If however this were to prove a heavy burden to a man on account of sickness, age, or some similar reason, he should be dispensed from fasting, or be allowed to forestall the hour by a little.
Art. 7 - Whether it is fitting that those who fast should be bidden to abstain from flesh meat, eggs, and milk foods? Objection 1: It would seem unfitting that those who fast should be bidden to abstain from flesh meat, eggs, and milk foods. ”

“ In like manner right reason does not retrench so much from a man's food as to render him incapable of fulfilling his duty. Hence Jerome says (in the same reference) "Rational man forfeits his dignity, if he sets fasting before chastity, or night-watchings before the well-being of his senses." ”

“ Wine and other things that heat the body conduce especially to heat: flatulent foods seemingly cooperate in the production of the vital spirit: but it is chiefly the use of flesh meat which is most productive of nourishment, that conduces to the production of humor. Now the alteration occasioned by heat, and the increase in vital spirits are of short duration, whereas the substance of the humor remains a long time. Hence those who fast are forbidden the use of flesh meat rather than of wine or vegetables which are flatulent foods. ”

“ Wherefore as long as the stage of growth lasts, which as a rule lasts until they have completed the third period of seven years, they are not bound to keep the Church fasts: and yet it is fitting that even during that time they should exercise themselves in fasting, more or less, in accordance with their age. ”

“ Those poor who can provide themselves with sufficient for one meal are not excused, on account of poverty, from keeping the fasts of the Church. On the other hand, those would seem to be exempt who beg their food piecemeal, since they are unable at any one time to have a sufficiency of food. ”

“ Now reason judges it expedient, on account of some special motive, for a man to take less food than would be becoming to him under ordinary circumstances, for instance in order to avoid sickness, or in order to perform certain bodily works with greater ease: and much more does reason direct this to the avoidance of spiritual evils and the pursuit of spiritual goods. ”

“ Now the poor are wont to fast through necessity, owing to lack of food. Much more therefore ought they to fast willingly.
On the contrary, It seems that no righteous man is bound to fast. For the commandments of the Church are not binding in opposition to Christ's teaching. But our Lord said (Lk. 5:34) that "the children of the bridegroom cannot fast whilst the bridegroom is with them [*Vulg.: 'Can you make the children of the bridegroom fast, whilst the bridegroom is with them?'] ." ”

“ Therefore, since fasting is directed to a spiritual gain, and is made a necessary thing by the commandment of the Church, it seems that the fasts of the Church ought not to be omitted on account of a pilgrimage, or bodily works. ”

“ Further, spiritual things should be preferred to temporal, and necessary things to those that are not necessary. Now bodily works are directed to temporal gain; and pilgrimages, though directed to spiritual things, are not a matter of necessity. ”

“ For this reason the eating of flesh meat is forbidden in every fast, while the Lenten fast lays a general prohibition even on eggs and milk foods. As to the use of the latter things in other fasts the custom varies among different people, and each person is bound to conform to that custom which is in vogue with those among whom he is dwelling. ”

“ Moreover at the Easter festival the mind of man ought to be devoutly raised to the glory of eternity, which Christ restored by rising from the dead, and so the Church ordered a fast to be observed immediately before the Paschal feast ”