(Greek mysterion, from myein, "to shut", "to close".)
This term signifies in general that which is unknowable, or valuable knowledge that is kept secret. In pagan antiquity the word mystery was used to designate certain esoteric doctrines, such as Pythagoreanism, or certain ceremonies that were performed in private or whose meaning was known only to the initiated, e.g., the Eleusinian rites, Phallic worship. In the language of the early Christians the mysteries were those religious teachings that were carefully guarded from the knowledge of the profane (see DISCIPLINE OF THE SECRET).
The Old-Testament versions use the word mysterion as an equivalent for the Hebrew sôd, "secret" (Proverbs 20:19; Judith 2:2; Sirach 22:27; 2 Maccabees 13:21). In the New Testament the word mystery is applied ordinarily to the sublime revelation of the Gospel (Matthew 13:11; Colossians 2:2; 1 Timothy 3:9; 1 Corinthians 15:51), and to the Incarnation and life of the Saviour and His manifestation by the preaching of the Apostles (Romans 16:25; Ephesians 3:4; 6:19; Colossians 1:26; 4:3).
In conformity with the usage of the inspired writers of the New Testament, theologians give the name mystery to revealed truths that surpass the powers of natural reason. Mystery, therefore, in its strict theological sense is not synonymous with the incomprehensible, since all that we know is incomprehensible, i.e., not adequately comprehensible as to its inner being; nor with the unknowable, since many things merely natural are accidentally unknowable, on account of their inaccessibility, e.g., things that are future, remote, or hidden. In its strict sense a mystery is a supernatural truth, one that of its very nature lies above the finite intelligence.
Theologians distinguish two classes of supernatural mysteries: the absolute (or theological) and the relative. An absolute mystery is a truth whose existence or possibility could not be discovered by a creature, and whose essence (inner substantial being) can be expressed by the finite mind only in terms of analogy, e.g., the Trinity. A relative mystery is a truth whose innermost nature alone (e.g., many of the Divine attributes), or whose existence alone (e.g., the positive ceremonial precepts of the Old Law), exceeds the natural knowing power of the creature.
The existence of theological mysteries is a doctrine of Catholic faith defined by the Vatican Council, which declares: "If any one say that in Divine Revelation there are contained no mysteries properly so called (vera et proprie dicta mysteria), but that through reason rightly developed (per rationem rite excultam) all the dogmas of faith can be understood and demonstrated from natural principles: let him be anathema" (Sess. III, Canons, 4. De fide et Ratione, 1). This teaching is clearly explained in Scripture. The principal proof text, which was cited in part by the Vatican Council, is 1 Corinthians 2. Shorter passages are especially Ephesians 3:4-9; Colossians 1:26-27; Matthew 11:25-27; John 1:17-18. These texts speak of a mystery of God, which only infinite wisdom can understand, namely, the designs of Divine Providence and the inner life of the Godhead (see also Wisdom 9:16-17; Romans 11:33-36). Tradition abounds with testimonies that support this teaching. In the Brief "Gravissimas Inter" (Denzinger, "Enchiridion", ed. Bannwart, nn. 1666-74), Pius IX defends the doctrine of supernatural mystery by many citations from the works of the Fathers. Numerous other patristic texts that bear on the same question are quoted and explained in Kleutgen's "Die Theologie der Vorzeit", II, 75 sq.; V, 220 sq.; and in Schäzler's "Neue Untersuchungen über das Dogma von der Gnade" (Mainz, 1867), 466 sq. The manifold excellence of Christian revelation offers many theological arguments for the existence of supernatural mysteries (cf. Scheeben, "Dogmatik", I, 24).
The existence of supernatural mysteries is denied by Rationalists and semi-Rationalists. Rationalists object that mysteries are degrading to reason. Their favourite argument is based on the principle that no medium exists between the reasonable and the unreasonable, from which they conclude that the mysterious is opposed to reason (Bayle, Pfleiderer). This argumentation is fallacious, since it confounds incomprehensibility with inconceivableness, superiority to reason with contradiction. The mind of a creature cannot, indeed, grasp the inner nature of the mysterious truth, but it can express that truth by analogies; it cannot fully understand the coherence and agreement of all that is contained in a mystery of faith, but it can refute successfully the objections which would make a mystery consist of mutually repugnant elements.
Rationalists further object that the revelation of mysteries would be useless, since it is the nature of reason to accept only the evident (Toland), and since the knowledge of the incomprehensible can have no influence on the moral life of mankind (Kant). To answer the first objection we have only to recall that there is a twofold evidence: the internal evidence of a thing in itself, and the external evidence of trustworthy authority. The mysteries of revelation, like the facts of history, are supported by external evidence and therefore they are evidently credible. The second difficulty rests on a false assumption. The religious life of the Christian is rooted in his faith in the supernatural, which is an anticipation of the beatific vision (St. Thomas, "Comp. Theol. ad fratrem Reg., " cap. ii), a profound act of religious homage (Contra. Gent., I, vi), and the measure by which he judges the world and the ways of God. The history of civilization bears witness to the beneficial influence that Christian faith has exerted on the general life of mankind (cf. Gutberlet, "Apologetik," II, 2 ed., Münster, 1895, 23).
Some Rationalists, trusting to far-fetched similarities, pretend that the Christian mysteries were borrowed from the religious and philosophical systems of Paganism. A study of the origin of Christianity suffices to show the absurdity of such an explanation. Semi-Rationalism explains mysteries either as purely natural truths expressed in symbolic language (Schelling, Baader, Sabatier), or as soluble problems of philosophy (Günther, Frohschammer). The errors of Günther were condemned in a pontifical letter to the Archbishop of Cologne in 1857, and in another to the Bishop of Breslau in 1860 (Denzinger, "Enchiridion", ed. Bannwart, nn. 1655-1658); those of Frohschammer, in the Brief "Gravissimas Inter", 11 Dec., 1862.
(a) Superiority of the Supernatural
The mysteries contained in supernatural revelation are not simply disconnected truths lying beyond the realm of natural things, but a higher, heavenly world, a mystical cosmos whose parts are united in a living bond. (Scheeben, "Dogmatik", I, 25.) Even in those parts of this vast system that have been revealed to us there is a wonderful harmony. In his great work "Die Mysterien des Christenthums", Scheeben has sought to show the logical connection in the supernatural order by considering its supreme mystery, the internal communication of Divine life in the Trinity, as the model and ideal of the external communication to the creature of the Divine life of grace and glory. The knowledge of the supernatural is more excellent than any human wisdom, because, although incomplete, it has a nobler object, and through its dependence on the unfailing word of God possesses a greater degree of certitude. The obscurity which surrounds the mysteries of faith results from the weakness of the human intellect, which, like the eye that gazes on the sun, is blinded by the fulness of light.
(b) Harmony of Natural and Supernatural Truth
Since all truth is from God, there can be no real warfare between reason and revelation. Supernatural mysteries as such cannot be demonstrated by reason, but the Christian apologist can always show that the arguments against their possibility are not conclusive (St. Thomas, "Suppl. Boeth. de trinitate", Q. ii, a. 3). The nature of God which is infinite and eternal, must be incomprehensible to an intelligence that is not capable of perfect knowledge (cf. Zigliara, "Propædeutica", I, ix). The powerlessness of science to solve the mysteries of nature, a fact that Rationalists admit, shows how limited are the resources of the human intellect (cf. Daumer, "Des Reich des Wundersamen und Geheimnissvollen," Ratisbon, 1872). On the other hand reason is able not only to recognize wherein consists the special mysteriousness of a supernatural truth, but also to dispel to some extent the obscurity by means of natural analogies and to show the fittingness of the mystery by reasons of congruity (Council of Cologne, 1860). This was done with great success by the Fathers and the Scholastic theologians. A famous example is St. Thomas' argument ex convenientia for the Divine processions in the Trinity (Summa Theol., I, QQ. xxvii-xxxi). (See FAITH, REASON, REVELATION.)