(discipline of the mysteries, or system of secret instruction), a term first introduced by Meier in his De Recondita vet. Eccles. Theologia (1677), to denote the practice of the early church of concealing from unbelievers, and even from catechumens, certain parts of divine worship, especially of the sacraments. The subject is curious in itself, and receives additional importance from the use made of it by the Romanists (see below). The disciplina arcani is not to be confounded with the system of reserve, or concealment in theology (scientia arcani, μυστηριοσοφία), which sprang up in Egypt in the second century, viz. the system adopted by certain teachers of not communicating certain parts of Christian knowledge (γνώσις) to Christian people generally, but only secretly to such as they deemed capable and worthy. Clement of Alexandria is the first to mention this system, and he pretends that it was instituted by Christ himself (Stromat. lib.1, c. 1; see Mosheim, Historical Commentaries, cent. 2, § 34). But the arcani disciplina proper referred to worship rather than to doctrine. It is fully treated by Bingham, from whom the following statement; is condensed.
1. Tertullian († 220) is the first writer who mentions the practice of this mystery, and blames the heretics for not observing it (De Prcescript. adv. Haer. cap. 41). — From him, and from later writers, it appears that the secret system at first covered only Baptism and the Lord's Supper (i.e. the forms and ritual of the sacraments, not the doctrine concerning them). At a later period, confirmation, ordination, and unction were also made matters of concealment; and parts of the prayers of the church were enjoyed only by the "faithful," while unbelievers and catechumens were excluded from them. The system seems to have reached its height during the fourth century. At that time catechumens were taught the Ten Commandments, a creed, or summary confession of faith, and the Lord's Prayer, with suitable expositions; but, prior to baptism, the nature of the sacraments was carefully concealed. Even the time and place were not on any account to be divulged. To relate the manner in which the sacrament was administered, to mention the words used in the administration, to describe the simple elements in which it consisted, were themes on which the initiated were as strictly forbidden to touch as if they had been laid under an oath of secrecy. Even the ministers, when they were led in their public discourses to speak of the sacraments or the higher doctrines of faith, contented themselves with remote allusions, and dismissed the subject by saying ςΙσασιν οἱ μεμυημένοι, The initiated know what is meant. So also of confirmation. Basil (De Spiritu Sancto, c. 27) says that the "holy oil used in this ceremony is not to be looked upon by the uninitiated." As to the public prayers of the church, all those which had reference to the communion service were confined to the fideles. The highest class of penitents, called consistentes, or co-standers, were allowed to be present at the communion prayers, and see the oblation offered and received by the faithful, though they might not partake with them. But catechumens of all ranks were wholly excluded from all this. They were always dismissed before these prayers began, and the doors of the church were locked and guarded by proper officers, to the intent that no uninitiated person should indiscreetly rush in upon them. We shut the doors, says Chrysostom (Hom. 23, in Matt.), when we celebrate the holy mysteries, and drive away all uninitiated persons. This was one of the secrets of the church, as we heard St. Austin before (in Psalm. 103) speak of it; one of the things which a catechumen might not look upon, according to St. Basil (De Spirit. Sanct. c. 27). Therefore the author of the Apostolical Constitution (lib. 2, c. 57; 8, c. 11) makes it a part of the deacon's office not only to command their absence, but also to keep the doors, that none might come in during the time of the oblation. Epiphanius (Haeres. 42, n. 3) and St. Jerome (Comm. in Galat. c. 6) bring it as a charge against the Marcionites that they despised this discipline, and admitted catechumens indiscriminately with the faithful to all their mysteries. And Palladius (Vita Chrysost. c. 9) forms a like charge against the enemies of Chrysostom, that in the tumult they raised against him, they gave occasion to the uninitiated to break into the church, and see those things which it was not lawful for them to set their eyes upon. Nay, so strict was the church then in the observation of this discipline, that Athanasius convicted the Meletians of false witness against him when they pretended to prove by the testimony of some catechumens that Macarius, one of his presbyters, had overturned the communion table in the time of the oblation; he argued that this could not be so, because (Athanasius, Apol. 2), if the catechumens were present, there could then be no oblation.(Bingham, Orig. Eccles. bk. 10, ch. 5.)
2. The disciplina arcani gradually fell into disuse; no precise date of its end can be given. Rothe (Herzog, Real-Encyklopadie, 1, 471) remarks that so long, on the one hand, as the church stood in the midst of a heathen world, and as long, on the other hand, as, within the church, delay of baptism (the procrastination baptismi) to an advanced age, or even to the dying hour, was practiced, the arcani disciplina might have been a useful system; but just in proportion as infant baptism became more general, and the pagan world was christianized, the secret discipline lost its significance; for, in consequence of these changes, the class of persons for whom it had been instituted no longer existed. In a general way, we may name the end of the sixth century as the period when it passed away. The Western Church gradually stripped its liturgy of all secret usages; and Bona (Rer. Liturgicar. 1. 1, 16, 6) asserts that about 700 the catechumenal system was entirely gone. The Eastern Church, however, holds on to her antiquated formulas, by which the catechumens are dismissed from divine worship, notwithstanding that church has no catechumens, and practices infant communion.
3. The original grounds for the adoption of the arcani disciplina cannot be known; but conjectures, and even plausible sources, are not wanting. The reasons for it were, according to Bingham, first, that the plainness and simplicity of the Christian rites might not be contemned by the catechumens, or give scandal or offense to them, before they were thoroughly instructed about the nature of the mysteries; secondly, to conciliate a reverence in the minds of men for the mysteries so concealed; and, thirdly, to make the catechumens more desirous to know them, or to excite their curiosity. Augustine says, "Though the sacraments are not disclosed to the catechumens, it is not because 'they cannot bear them, but that they may so much the more ardently desire them, by how much they are more honorably hidden from them" (Hom. in Joh. 96). Plothe goes into an elaborate inquiry on the subject in the article above cited (and also in his treatise De Disciplinae Arcani Origine (Heidel. 1841, 4to), of which the following is the substance. Casaubon (De reb. sacris Exerc. 16, Genev. 1654, 4to) traces the origin of it to a desire, on the part of Christians, to have mysteries of their own, and so not to be outdone by heathenism, which set great store by them. Rothe disputes this, ton the ground of the bitter opposition of the Anti-Nicene Christians to all heathen ideas and usages. But he forgets that mysteries are congenial to human nature in all ages; a spirit akin to that which preserves Free-masonry could very well have existed in the early church. With less probability, certain writers, e.g. Frommann (De Disciplina Arcani, Jena; — 1833), find the origin of the secret system in Judaism, which did not admit proselytes at once to all sacred services. Had this been so, we should find traces of it in the N.T. and in the apostolic age; but the whole system is quite foreign to apostolic usage, which practiced the utmost openness. Moreover, during that early period of Christianity when the church borrowed from Judaism, the disciplina arcani did not yet exist; and besides, the Jewish custom appears to be of so late an origin that it may itself be an imitation of a Christian institution. Augusti (Handb. der Christl. Archaologie, 1, 93 sq.; Denkwurdigkeiten, 4, 397) thinks that the early Christians adopted the secret discipline because their public worship was forbidden by law, and that this compulsory secrecy grew into a usage. But: if this were true, all parts of worship would have shared in the secrecy, whereas only certain portions were made mysteries of. Credner (Jenl. Literatur-Zeitung, 1846.
Nos. 164 and 165) traces the origin of the secret discipline back to the apostolic age, and finds the ground of it in the natural unwillingness of Jewish Christians to admit heathen converts at once to baptism. He finds confirmation of his theory in the fact that Clement of Alexandria (Quis Dives, c. 42), Ireneus (adv. Haer. 4:23, 24), and Tertullian (De Baptismo, c. 18) trace the origin of the catechumenate back to the apostles. But even this would not prove his point; there might be, and for some time were, catechumens, without a disciplina arcani; and, moreover, there is ample proof of openness in ritual usages up to the second century. But yet the true origin ofthe secret discipline is doubtless to be found in the catechumenate (see Rothe, l. c.). The catechumens were probationers in the church, not full members; and this novitiate was designed, first, to keep unworthy persons out of the church, and, secondly, to train new converts in Christian doctrine and morals. At this day the Methodist Episcopal Church has such a catechumenate (Discipline, ch. 2, § 1), but without any secret discipline. But in the early church, during the persecutions, it was dangerous at once to admit professed converts, who might be spies, into the assemblies of the faithful. They were accordingly taught apart. But the tendency of this state of things would naturally be to make two kinds of Christianity, the esoteric, or that of the baptized believers (fideles), and the exoteric, or that of the unbaptized catechumens. The former shared in the Lord's Supper, but not the latter. Here is a plain starting-point for making mysteries of the two sacraments in liturgical practice as well as in theory. What was at first accidental finally grew into a rule.
4. The Romanists, as remarked above, have attempted to press the disciplina arcani into their service to account for the silence of the early church writers as to penance, image-worship, and other of their corruptions. The Jesuit Schelstrate first attempted this in his Antiquitas illustrata (Ant. 1678), but was fully refuted by Tenzel in Exercitationes Selectce (Francof. 1692, 4to). Other Roman Catholic works on the subject are, Schollner, De Disciplina Arcani (Venet. 1756); Lienhardt, De Antiq. Liturg. et de Disciplina Arcani (Argentor. 1829). When pressed hard by Protestants with the argument that no traces of the corruptions named above, or of the invocation of saints, the seven sacraments, or transubstantion, are to be found in the early ages of the church, they admit the fact of this silence, but account for it on the ground that these doctrines and usages formed part of the disciplina arcani. Bingham shrewdly remarks that this "is an artifice that would justify as many errors and vanities as any church could be guilty of; it is but working a little with this admirable instrument and tool, called disciplina arcani, and then all the seeming contradictions between the ancient doctrines and practices of the church universal and the novel corruptions of the modern Church of Rome will presently vanish and disappear; so that we need not wonder why men, whose interest it serves so much, should magnify this as a noble invention" (bk. 10, ch. 5, § 1). The account given above of the nature of the arcane disciplina suffices of itself to refute the Romish pretense. The very mysteries themselves (baptism and the Eucharist), which formed the objects of the secret discipline, so far from being avoided by the early Christian writers, are topics of constant remark and discussion from the apostles' time downward. The bare fact, for instance, that the administration of the Eucharist was concealed from the catechumens, gives no more ground to suppose that transubstantiation was. taught in the bread and wine, than the fact that baptism was concealed from them gives around to suppose that the same doctrine was taught in the water of baptism. See Bingham, Orig. Ecclcs. bk. 10, ch. 5, and the other writers above cited. See also Neander, Church History, 1, 308; Coleman, Ancient Christianity, ch. 17, § 2; Herzog, Real-Encyklopdaie, 1, 467 sq. SEE MYSTERY.