Here's the Catholic Encyclopedia article on "Epiklesis", by Fr. Adrian Fortescue:
Epiklesis (Lat. invocatio) is the name of a prayer that occurs in all Eastern liturgies (and originally in Western liturgies also) after the words of Institution, in which the celebrant prays that God may send down His Holy Spirit to change this bread and wine into the Body and Blood of His Son. This form has given rise to one of the chief controversies between the Eastern and Western Churches, inasmuch as all Eastern schismatics now believe that the Epiklesis, and not the words of Institution, is the essential form (or at least the essential complement) of the sacrament.
Form of the Epiklesis
It is certain that all the old liturgies contained such a prayer. For instance, the Liturgy of the Apostolic Constitutions, immediately after the recital of the words of Institution, goes on to the Anamnesis -- "Remembering therefore His Passion..." -- in which occur the words: "thou, the God who lackest nothing, being pleased with them (the Offerings) for the honour of Thy Christ, and sending down Thy Holy Spirit on this sacrifice, the witness of the Passion of the Lord Jesus, to manifest (opos apophene) this bread as the Body of Thy Christ and this chalice as the Blood of Thy Christ..." (Brightman, Liturgies Eastern and Western, I, 21). So the Greek and Syrian Liturgies of St. James (ibid., 54, 88-89), the Alexandrine Liturgies (ibid., 134, 179), the Abyssinian Rite (ibid., 233), those of the Nestorians (ibid., 287) and Armenians (ibid., 439). The Epiklesis in the Byzantine Liturgy of St. John Chrysostom is said thus: "We offer to Thee this reasonable and unbloody sacrifice; and we beg Thee, we ask Thee, we pray Thee that Thou, sending down Thy Holy Spirit on us and on these present gifts" (the Deacon says: "Bless, Sir the holy bread") "make this bread into the Precious Body of Thy Christ" (Deacon: "Amen. Bless, Sir, the holy chalice"): "and that which is in this chalice, the Precious Blood of Thy Christ" (Deacon: "Amen. Bless, Sir, both"), "changing [metabalon] them by Thy Holy Spirit" (Deacon: "Amen, Amen, Amen."). (Brightman, op. cit., I 386-387).
Nor is there any doubt that the Western rites at one time contained similar invocations. The Gallican Liturgy had variable forms according to the feast. That for the Circumcision was: "Hæc nos, Domine, instituta et præcepta retinentes suppliciter oramus uti hoc sacrificium suscipere et benedicere et sanctificare digneris: ut fiat nobis eucharistia legitima in tuo Filiique tui nomine et Spiritus sancti, in transformationem corporis ac sanguinis domini Dei nostri Jesu Christi unigeniti tui, per quem omnia creas..." (Duchesne, "Origines du culte chrétien", 2nd ed., Paris, 1898, p. 208, taken from St. Germanus of Paris, d. 576). There are many allusions to the Gallican Invocation, for instance St. Isidore of Seville (De eccl. officiis, I, 15, etc.). The Roman Rite too at one time had an Epiklesis after the words of Institution. Pope Gelasius I (492-496) refers to it plainly: "Quomodo ad divini mysterii consecrationem coelestis Spiritus adveniet, si sacerdos...criminosis plenus actionibus reprobetur?" ("Epp. Fragm.", vii, in Thiel, "Epp. Rom. Pont.", I, 486). Watterich (Der Konsekrationsmoment im h. Abendmahl, 1896, pp. 133 sq.) brings other evidences of the old Roman Invocation. he (p. 166) and Drews (Entstehungsgesch. des Kanons, 1902, p. 28) think that several secrets in the Leonine Sacramentary were originally Invocations (see article CANON OF THE MASS). Of the essential clause left out -- our prayer: "Supplices te rogamus" (Duchesne, op. cit., 173-5). It seems that an early insistence on the words of Institution as the form of Consecration (see, for instance, Pseudo-Ambrose, "De Mysteriis", IX, 52, and "De Sacramentis", IV, 4, 14-15, 23; St. Augustine, Sermon 227) led in the West to the neglect and mutilation of the Epiklesis.
It should be noticed that the Epiklesis for the Holy Eucharist is only one of many such forms. In other sacraments and blessings similar prayers were used, to ask God to send His Holy Spirit to sanctify the matter. There was an Epiklesis for the water of baptism. Tertullian (De bapt., iv), Optatus of Mileve ("De schism. Don., III, ii, VI, iii, in "Corp. Script. eccl. Latin.", vol. XXVI, 69, 148, 149), St. Jerome (Contra Lucif., vi, vii), St. Augustine (De bapt., V, xx, xxvii), in the West; and St. Basil (De Spir. Sancto, xv, 35), St. Gregory of Nyssa (Orat. cat. magn. xxxiii), and St. Cyril of Jerusalem (Cat. iii, 3), in the East, refer to it. In Egypt especially, Epiklesis were used to bless wine, oil, milk, etc. In all these cases (including that of the Holy Eucharist) the idea of invoking the Holy Ghost to sanctify is a natural one derived from Scripture (Joel 2:32; Acts 2:21: ho an epikalesetai to onoma kyriou . . .; cf. Romans 10:13; 1 Corinthians 1:2). That in the Liturgy the Invocation should occur after the words of Institution is only one more case of many which show that people were not much concerned about the exact instant at which all the essence of the sacrament was complete. They looked upon the whole Consecration-prayer as one simple thing. In it the words of Institution always occur (with the doubtful exception of the Nestorian Rite); they believed that Christ would, according to His promise, do the rest. But they did not ask at which exact moment the change takes place. Besides the words of Institution there are many other blessings, prayers, and signs of the cross, some of which came before and some after the words, and all, including the words themselves, combine to make up the one Canon of which the effect is Transubstantiation. So also in our baptism and ordination services, part of the forms and prayers whose effect is the sacramental grace comes, in order of time, after the essential words. It was not till Scholastic times that theologians began to discuss the minimum of form required for the essence of each sacrament.
The Catholic Church has decided the question by making us kneel and adore the Holy Eucharist immediately after the words of Institution, and by letting her old Invocation practically disappear. On the other hand Orthodox theologians all consider the Epiklesis as being at least an essential part of the Consecration. In this question they have two schools. Some, Peter Mogilas, for instance, consider the Epiklesis alone as consecrating (Kimmel, Monumenta fidei eccl. orient., Jena, 1850, I, 180), so that presumably the words of Institution might be left out without affecting the validity of the sacrament. But the greater number, and now apparently all, require the words of Institution too. They must be said, not merely historically, but as the first part of the essential form; they sow as it were the seed that comes forth and is perfected by the Epiklesis. Both elements, then, are essential. This is the theory defended by their theologians at the Council of Florence (1439). A deputation of Latins and Greeks was appointed then to discuss the question. The Greeks maintained that both forms are necessary, that Transubstantiation does not take place till the second one (the Epiklesis) is pronounced, and that the Latin "Supplices te rogamus" is a true Epiklesis having the same effect as theirs. On the other hand the Dominican John of Torquemada defended the Western position that the words of Institution alone and at once consecrate (Hardouin, IX, 977 sqq.). The decree of the council eventually defined this "quod illa verba divina Salvatoris omnem virtutem transsubstantiationis habent," ibid.; see also the decree for the Armenians: "forma huius sacramenti sunt verba Salvatoris" in Denziger, 10th ed., no. 698-old no. 593). Cardinal Bessarion afterwards wrote a book "De Sacramento Eucharistiæ et quibus verbis Christi corpus conficitur, 1462, in P. G., CLXI, 494-525), to whom Marcus Eugenicus of Ephesus answered in a treatise with a long title: "That not only by the sound of the Lord's words are the divine gifts sanctified, but (in addition) by the prayer after these and by the consecration of the priest in the strength of the Holy Ghost."
The official Euchologion of the Orthodox Church has a note after the words of Institution to explain that: "Since the demonstrative pronouns: This is my body, and again: This is my blood, do not refer to the Offerings that are present, but to those which Jesus, taking in His hands and blessing, gave to His Disciples; therefore those words of the Lord are repeated as a narrative [diegematikos], and consequently it is superfluous to show the Offerings (by an elevation) and indeed contrary to the right mind of the Eastern Church of Christ" (ed. Venice, 1898, p. 63). This would seem to imply that Christ's words have no part in the form of the sacrament. On the other hand Dositheus in the Synod of Jerusalem (1672) apparently requires both words of Institution and Epiklesis: "It [the Holy Eucharist] is instituted by the essential word [remati uparktiko, i.e. Christ's word] and sanctified by the invocation of the Holy Ghost" (Conf. Dosithei, in Kimmel, op. cit., I, 451), and this seems to be the common theory among the Orthodox in our time. Their arguments for the necessity of the Epiklesis as at any rate the perfecting part of the form are:
- that the context shows the words of Institution to be used only as a narrative;
- that otherwise the Epiklesis would be superfluous and deceptive: its very form shows that it consecrates;
The first and second points are not difficult to answer. The words of Institution are certainly used historically ("qui pridi quam pateretur, sumpsit panem...ac dixit: hoc est enim corpus meum," as well as all Eastern forms, is an historical account of what happened at the Last Supper); but this is no proof that they may not be used effectively and with actual meaning too. Given the intention of so doing, they necessarily would be so used. The second point is already answered above: the succession of time in sacramental prayers necessarily involves nothing but a dramatic representation of what presumably really takes place in one instant (this point is further evolved by Fortescue, "The Orth. Eastern Church," pp. 387 sq.). As for tradition, in any case it is only a question of Eastern tradition. In the West there has been a great unanimity in speaking of the words of Institution as consecrating, especially since St. Augustine; and the disapperance of any real Epiklesis in our Liturgy confirms this. Among Eastern Fathers there is less unanimity. Some, notably St. Cyril of Jerusalem, refer the consecration to the action of the Holy Ghost in a way that seems to imply that the Epiklesis is the moment (St. Cyril, Cat. xix, 7; xxi, 3; xxiii, 7, 19; cf. Basil, "De Spir. Sancto," xxvii sqq.); others, as St. John Chrysostom (Hom. i, De prod. Iudæ, 6: "He [Christ] says: This is my body. This word changes the offering"; cf. Hom. ii, in II Tim., i), quite plainly refer Consecration to Christ's words. It should be noted that these Fathers were concerned to defend the Real Presence, not to explain the moment at which it began, that they always thought of the whole Eucharistic prayer as one form, containing both Christ's words and the Invocation, and that a statement that the change takes place by the power of the Holy Ghost does not necessarily show that the writer attaches that change to this special prayer. For instance St. Irenæus says that "the bread which receives the Invocation of God is not common bread, but a Eucharist" (Adv. hær., IV, xviii, 5), and, yet immediately before (IV, xviii, 4), he explains that that bread is the Body of Christ over which the earlier part of the Anaphora is said. The final argument against the Epiklesis as Consecration-form is the account of the Last Supper in the Gospels. We know what Christ did then, and that He told us to do the same thing. There is no hint of an Epiklesis at the Last Supper.
It may finally be noted that later, in the West too (since the sixteenth century especially), this question aroused some not very important discussion. The Dominican Ambrose Catharinus (sixteenth century) thought that our Consecration takes place at an Epiklesis that precedes the recital of Christ's words. This Epiklesis he thinks to be the prayer "Quam oblationem." A few others (including Renaudot) more or less shared his opinion. Against these Hoppe (op. cit. infra) showed that in any case the Epiklesis always follows the words of Institution and that our "Quam Oblationem" cannot be considered one at all. He and others suggest a mitigated theory, according to which the Invocation (in our case the "Supplice te rogamus") belongs not to the essence of the sacrament, but in some way to its (accidental) integrity. John of Torquemada at the Council of Florence (Hardouin, IX, 976), Suarez (De Sacram., disp. lviii, 3), Bellarmine (De Euch., iv, 14), Lugo (De Euch., disp. xi, 1) explain that the Invocation of the Holy Ghost is made rather that He may sanctify our reception of the Holy Eucharist. This is a theoretical explanation sought out to account for the fact of the Epiklesis, without giving up our insistence on the words of Institution as alone consecrating. Historically and according to the text of the old invocations they must rather be looked upon as dramatically postponed expressions of what happens at one moment. There are many like cases in our rite (examples quoted in "The Orth. Eastern Church," loc. cit.).
Written by Adrian Fortescue. Transcribed by Tim Drake.
The Catholic Encyclopedia, Volume V. Published 1909. New York: Robert Appleton Company. Nihil Obstat, May 1, 1909. Remy Lafort, Censor. Imprimatur. +John M. Farley, Archbishop of New York