The following text is quoted from John Calvin’s Institutes of the Christian Religion, Book IV, Chapter 12, sections 14-21.
14. The remaining part of discipline, which is not, strictly speaking, included in the power of the keys, is when pastors, according to the necessity of the times, exhort the people either to fasting and solemn prayer, or to other exercises of humiliation, repentance, and faith, the time, mode, and form of these not being prescribed by the Word of God, but left to the judgment of the Church. As the observance of this part of discipline is useful, so it was always used in the Church, even from the days of the apostles. Indeed, the apostles themselves were not its first authors, but borrowed the example from the Law and Prophets. For we there see, that as often as any weighty matter occurred the people were assembled, and supplication and fasting appointed. In this, therefore, the apostles followed a course which was not new to the people of God, and which they foresaw would be useful. A similar account is to be given of the other exercises by which the people may either be aroused to duty, or kept in duty and obedience. We everywhere meet with examples in Sacred History, and it is unnecessary to collect them. In general, we must hold that whenever any religious controversy arises, which either a council or ecclesiastical tribunal behoves to decide; whenever a minister is to be chosen; whenever, in short, any matter of difficulty and great importance is under consideration: on the other hand, when manifestations of the divine anger appear, as pestilence, war, and famine, the sacred and salutary custom of all ages has been for pastors to exhort the people to public fasting and extraordinary prayer. Should any one refuse to admit the passages which are adduced from the Old Testament, as being less applicable to the Christian Church, it is clear that the apostles also acted thus; although, in regard to prayer, I scarcely think any one will be found to stir the question. Let us, therefore, make some observations on fasting, since very many, not understanding what utility there can be in it, judge it not to be very necessary, while others reject it altogether as superfluous. Where its use is not well known it is easy to fall into superstition.
15. A holy and lawful fast has three ends in view. We use it either to mortify and subdue the flesh, that it may not wanton, or to prepare the better for prayer and holy meditation; or to give evidence of humbling ourselves before God, when we would confess our guilt before him. The first end is not very often regarded in public fasting, because all have not the same bodily constitution, nor the same state of health, and hence it is more applicable to private fasting. The second end is common to both, for this preparation for prayer is requisite for the whole Church, as well as for each individual member. The same thing may be said of the third. For it sometimes happens that God smites a nation with war or pestilence, or some kind of calamity. In this common chastisement it behoves the whole people to plead guilty, and confess their guilt. Should the hand of the Lord strike any one in private, then the same thing is to be done by himself alone, or by his family. The thing, indeed, is properly a feeling of the mind. But when the mind is effected as it ought, it cannot but give vent to itself in external manifestation, especially when it tends to the common edification, that all, by openly confessing their sin, may render praise to the divine justice, and by their example mutually encourage each other.
16. Hence fasting, as it is a sign of humiliation, has a more frequent use in public than among private individuals, although as we have said, it is common to both. In regard, then, to the discipline of which we now treat, whenever supplication is to be made to God on any important occasion, it is befitting to appoint a period for fasting and prayer. Thus when the Christians of Antioch laid hands on Barnabas and Paul, that they might the better recommend their ministry, which was of so great importance, they joined fasting and prayer (Acts 13:3). Thus these two apostles afterwards, when they appointed ministers to churches, were wont to use prayer and fasting (Acts 14:23). In general, the only object which they had in fasting was to render themselves more alert and disencumbered for prayer. We certainly experience that after a full meal the mind does not so rise toward God as to be borne along by an earnest and fervent longing for prayer, and perseverance in prayer. In this sense is to be understood the saying of Luke concerning Anna, that she “served God with fastings and prayers, night and day” (Luke 2:37). For he does not place the worship of God in fasting, but intimates that in this way the holy woman trained herself to assiduity in prayer. Such was the fast of Nehemiah, when with more intense zeal he prayed to God for the deliverance of his people (Neh. 1:4). For this reason Paul says, that married believers do well to abstain for a season (1 Cor. 7:5), that they may have greater freedom for prayer and fasting, when by joining prayer to fasting, by way of help, he reminds us it is of no importance in itself, save in so far as it refers to this end. Again, when in the same place he enjoins spouses to render due benevolence to each other, it is clear that he is not referring to daily prayer, but prayers which require more than ordinary attention.
17. On the other hand, when pestilence begins to stalk abroad, or famine or war, or when any other disaster seems to impend over a province and people (Esther 4:16), then also it is the duty of pastors to exhort the Church to fasting, that she may suppliantly deprecate the Lord’s anger. For when he makes danger appear, he declares that he is prepared and in a manner armed for vengeance. In like manner, therefore, as persons accused were anciently wont, in order to excite the commiseration of the judge, to humble themselves suppliantly with long beard, dishevelled hair, and coarse garments, so when we are charged before the divine tribunal, to deprecate his severity in humble raiment is equally for his glory and the public edification, and useful and salutary to ourselves. And that this was common among the Israelites we may infer from the words of Joel. For when he says, “Blow the trumpet in Zion, sanctify a fast, call a solemn assembly,” &c. (Joel 2:15), he speaks as of things received by common custom. A little before he had said that the people were to be tried for their wickedness, and that the day of judgment was at hand, and he had summoned them as criminals to plead their cause: then he exclaims that they should hasten to sackcloth and ashes, to weeping and fasting; that is, humble themselves before God with external manifestations. The sackcloth and ashes, indeed, were perhaps more suitable for those times, but the assembly, and weeping and fasting, and the like, undoubtedly belong, in an equal degree, to our age, whenever the condition of our affairs so requires. For seeing it is a holy exercise both for men to humble themselves, and confess their humility, why should we in similar necessity use this less than did those of old? We read not only that the Israelitish Church, formed and constituted by the word of God, fasted in token of sadness, but the Ninevites also, whose only teaching had been the preaching of Jonah. Why, therefore, should not we do the same? But it is an external ceremony, which, like other ceremonies, terminated in Christ. Nay, in the present day it is an admirable help to believers, as it always was, and a useful admonition to arouse them, lest by too great security and sloth they provoke the Lord more and more when they are chastened by his rod. Accordingly, when our Saviour excuses his apostles for not fasting, he does not say that fasting was abrogated, but reserves it for calamitous times, and conjoins it with mourning. “The days will come when the bridegroom shall be taken from them” (Mt. 9:35; Luke 5:34).
18. But that there maybe no error in the name, let us define what fasting is; for we do not understand by it simply a restrained and sparing use of food, but something else. The life of the pious should be tempered with frugality and sobriety, so as to exhibit, as much as may be, a kind of fasting during the whole course of life. But there is another temporary fast, when we retrench somewhat from our accustomed mode of living, either for one day or a certain period, and prescribe to ourselves a stricter and severer restraint in the use of that ordinary food. This consists in three things—viz. the time, the quality of food, and the sparing use of it. By the time I mean, that while fasting we are to perform those actions for the sake of which the fast is instituted. For example, when a man fasts because of solemn prayer, he should engage in it without having taken food. The quality consists in putting all luxury aside, and, being contented with common and meaner food, so as not to excite our palate by dainties. In regard to quantity, we must eat more lightly and sparingly, only for necessity and not for pleasure.
19. But the first thing always to be avoided is, the encroachment of superstition, as formerly happened, to the great injury of the Church. It would have been much better to have had no fasting at all, than have it carefully observed, but at the same time corrupted by false and pernicious opinions, into which the world is ever and anon falling, unless pastors obviate them by the greatest fidelity and prudence. The first thing is constantly to urge the injunction of Joel, “Rend your heart, and not your garments” (Joel 2:13); that is, to remind the people that fasting in itself is not of great value in the sight of God, unless accompanied with internal affection of the heart, true dissatisfaction with sin and with one’s self, true humiliation, and true grief, from the fear of God; nay, that fasting is useful for no other reason than because it is added to these as an inferior help. There is nothing which God more abominates than when men endeavour to cloak themselves by substituting signs and external appearance for integrity of heart. Accordingly, Isaiah inveighs most bitterly against the hypocrisy of the Jews, in thinking that they had satisfied God when they had merely fasted, whatever might be the impiety and impure thoughts which they cherished in their hearts. “Is it such a fast that I have chosen?” (Isa. 58:5) See also what follows. The fast of hypocrites is, therefore, not only useless and superfluous fatigue, but the greatest abomination. Another evil akin to this, and greatly to be avoided, is, to regard fasting as a meritorious work and species of divine worship. For seeing it is a thing which is in itself indifferent, and has no importance except on account of those ends to which it ought to have respect, it is a most pernicious superstition to confound it with the works enjoined by God, and which are necessary in themselves without reference to anything else. Such was anciently the dream of the Manichees, in refuting whom Augustine clearly shows, that fasting is to be estimated entirely by those ends which I have mentioned, and cannot be approved by God, unless in so far as it refers to them. Another error, not indeed so impious, but perilous, is to exact it with greater strictness and severity as one of the principal duties, and extol it with such extravagant encomiums as to make men imagine that they have done something admirable when they have fasted. In this respect I dare not entirely excuse ancient writers from having sown some seeds of superstition, and given occasion to the tyranny which afterwards arose. We sometimes meet with sound and prudent sentiments on fasting, but we also ever and anon meet with extravagant praises, lauding it as one of the cardinal virtues.
20. Then the superstitious observance of Lent had everywhere prevailed: for both the vulgar imagined that they thereby perform some excellent service to God, and pastors commended it as a holy imitation of Christ; though it is plain that Christ did not fast to set an example to others, but, by thus commencing the preaching of the gospel, meant to prove that his doctrine was not of men, but had come from heaven. And it is strange how men of acute judgment could fall into this gross delusion, which so many clear reasons refute: for Christ did not fast repeatedly (which he must have done had he meant to lay down a law for an anniversary fast), but once only, when preparing for the promulgation of the gospel. Nor does he fast after the manner of men, as he would have done had he meant to invite men to imitation; he rather gives an example, by which he may raise all to admire rather than study to imitate him. In short, the nature of his fast is not different from that which Moses observed when he received the law at the hand of the Lord (Exod. 24:18; 34:28). For, seeing that that miracle was performed in Moses to establish the law, it behoved not to be omitted in Christ, lest the gospel should seem inferior to the law. But from that day, it never occurred to any one, under pretence of imitating Moses, to set up a similar form of fast among the Israelites. Nor did any of the holy prophets and fathers follow it, though they had inclination and zeal enough for all pious exercises; for though it is said of Elijah that he passed forty days without meat and drink (1 Kings 19:8), this was merely in order that the people might recognise that he was raised up to maintain the law, from which almost the whole of Israel had revolted. It was therefore merely false zeal, replete with superstition, which set up a fast under the title and pretext of imitating Christ; although there was then a strange diversity in the mode of the fast, as is related by Cassiodorus in the ninth book of the History of Socrates: “The Romans,” says he, “had only three weeks, but their fast was continuous, except on the Lord’s day and the Sabbath. The Greeks and Illyrians had, some six, others seven, but the fast was at intervals. Nor did they differ less in the kind of food: some used only bread and water, others added vegetables; others had no objection to fish and fowls; others made no difference in their food.” Augustine also makes mention of this difference in his latter epistle to Januarius.
21. Worse times followed. To the absurd zeal of the vulgar were added rudeness and ignorance in the bishops, lust of power, and tyrannical rigour. Impious laws were passed, binding the conscience in deadly chains. The eating of flesh was forbidden, as if a man were contaminated by it. Sacrilegious opinions were added, one after another, until all became an abyss of error. And that no kind of depravity might be omitted, they began, under a most absurd pretence of abstinence, to make a mock of God; for in the most exquisite delicacies they seek the praise of fasting: no dainties now suffice; never was there greater abundance or variety or savouriness of food. In this splendid display they think that they serve God. I do not mention that at no time do those who would be thought the holiest of them wallow more foully. In short, the highest worship of God is to abstain from flesh, and, with this reservation, to indulge in delicacies of every kind. On the other hand, it is the greatest impiety, impiety scarcely to be expiated by death, for any one to taste the smallest portion of bacon or rancid flesh with his bread. Jerome, writing to Nepotian, relates, that even in his day there were some who mocked God with such follies: those who would not even put oil in their food caused the greatest delicacies to be procured from every quarter; nay, that they might do violence to nature, abstained from drinking water, and caused sweet and costly potions to be made for them, which they drank, not out of a cup, but a shell. What was then the fault of a few is now common among all the rich: they do not fast for any other purpose than to feast more richly and luxuriously. But I am unwilling to waste many words on a subject as to which there can be no doubt. All I say is, that, as well in fasts as in all other parts of discipline, the Papists are so far from having anything right, anything sincere, anything duly framed and ordered, that they have no occasion to plume themselves as if anything was left them that is worthy of praise.