I. Definition of Perichoresis. — The no-

tion of Perichoresis ( Trcpix^prjons or (nj/xTreptx Latin circiimincessio, later circuminsessio) em- braces two essential elements: (a) Duality in unity and (b) Unity in duality. The former is the material, the latter the formal element.
In other words: The mutually in-existing substances must be (i) really distinct and (2) substantially one. Without a real distinction there would be no Perichoresis but absolute identity; without substantial unity the two substances would merely co-exist side by side.
The specific nature of Perichoresis depends entirely on the manner in which the elements are combined in one unum substantiale. Trinitarian differs essentially from Christological Perichoresis, is its exact counterpart in fact, because the mutual relations of nature and person in the Blessed Trinity and in Christ are precisely con-
179
i8o UNITY IN DUALITY
trary.^ " As in the Trinity, three Persons exist in one nature, so in the Word Incarnate, two natures exist in one Person, and therefore the Fathers appHed the term Perichoresis to both mysteries. But as Trinitarian Perichoresis proceeds, so to speak, from the statical pos- session of a common nature, so in the mystery of the Incarnation Perichoresis is based upon the Hypostatic Union, i. e., that powerful magnet by which the human nature is drawn into substantial communion with the Godhead. This latter Perichoresis reaches its climax in the effective interpenetration of both natures in Christ's theandric operation." ^ In Christ, therefore, the bond which unites Godhead and manhood is the Divine Person of the Logos, who possesses at once two natures inti- mately united, indwelling in each other by virtue of the Hypostatic Union.*
Considered in relation to the Hypostatic Union, Peri- choresis is its counterpart rather than an effect flowing therefrom. For, as Oswald truly observes, " The Sym- perichoresis of the two natures, effected by personal unity, is merely the reverse side of that personal unity by which it is effected ; the two complement each other and together constitute the perfect expression of the hypostatic or physical union." ° According to our hu- man mode of conception, the Hypostatic Union precedes Perichoresis as a condition precedes that which it con- ditions, and therefore we conceive the latter as an effect of the former.
In Christology, therefore, Perichoresis may be defined as "the mutual in-existence of the two
2 V. supra, pp. 3 sq. awv Tuy (piffeiop els dXXiJXas t
8.L. Jansscns, De Deo-Hotnine, \67y rijs avfKpvttli,
Vol. I, p. 684, Freiburg 1901. 5 Oswald, Christologie, p. 160, and
4Cfr. St. Gregory of Nazianzus, ed., Paderborn 1887.
Ep. loi ad Cledon.: Kal wepiX'^P'^^-
CHRISTOLOGICAL PERICHORESIS i8i
unmixed natures (the divine and the human) by reason of their hypostatic union with the Person of the Logos."
2. The Power of Perichoresis. — In con- formity with our previous teaching in regard to the immutabihty of the Logos,^ we claim that the power which unifies and binds together the two natures in Perichoresis cannot proceed from the humanity of Christ; it must originate in the Divine Logos, who, despite His own impene- trabihty, in a manner ineffable and mysterious, seizes, penetrates, and immerses Himself in the human nature, and thus becomes o 0£os Ao'yos ivav6pwTri](xa
a) Leporius describes this process somewhat tech- nically as follows : " Deus qui capax est, non capabilis, penetrans, non penetrabilis, implens, non implebilis, qui ubique simul totus et ubique diifusus per infusionem potentiae suae misericorditer naturae mixtus est humanae, non humana natura naturae est mixta divinae. Caro igitur proHcit in Verbum, non Verbum proficit in carnem, et tamen verissime Verbum caro factum est." '' Peri- choresis is therefore not a mutual interpenetration {com- penetratio mutua) ; it must rather be defined as a mu- tual in-existence ( inexistentia mutua) of the two natures in Christ. Human nature, being a created substance, can- not be immersed in the Logos in the same way in which the immutable Logos immerses itself in it. St. John of
6 V. supra, pp. 121 sq. clator Literar. Theologiae Catholicae,
7 Libell. Emend., n. 4. On the Vol. I, 3rd ed., col. 287, Innsbruck monk Leporius and his Libetlus 1903.
Emendationis cfr. Hurter, Nomen-
i82 UNITY IN DUALITY
Damascus puts it thus : " The penetration does not pro- ceed from the flesh, but from the Godhead. For it is impossible that the flesh should permeate the Godhead; but by penetrating into the flesh, the Divine Nature has endowed the flesh with an inexplicable penetration of itself, which is called unition." *
b) In view of this dissimilarity, there can be no doubt as to what the holy Fathers mean when they speak of a " deificatio humanitatis " and refer to the flesh of Christ as " vivifica" The term deificatio (^et'wo-ts) does not signify apotheosis in the Monophysitic sense. It is rather to be taken as indicating merely the deification of Christ's manhood through the medium of Perichoresis or the Hypostatic Union. St. John Damascene says: " From the time that God the Word became flesh. He is as we are in everything except sin, and of our na- ture without confusion. He has deified our flesh for ever through the mutual interpenetration of His Godhead and His flesh without confusion." ° Consequently the ^eitoCTts is not based on (Tvyxv(ri the two natures resulting from their Hypostatic Union. To deification thus defined there corresponds as a prac- tical correlative the " vivifying power of Christ's flesh," because His humanity (which is what is meant by flesh), represents a " second nature " hypostatically incor- porated with and intimately possessed by the Divine Lo- gos, which (second nature) as instrument urn coniunctum, produces truly theandric eflfects.^" "Si quis non coniite-
8 De Fide Orthodoxa, III, 19: inexplicabilem in se ipsam «m-
" Commcatio non ex came, sed ex meationem, guam unitionetn vo-
diviniiate facta est. Impossibile est cant,"
eniin carncm pcrmeare divinitatem; 0 Or, de Imagin,, I, 21.
sed divina nalura quum per carnem 10 V. supra, pp. 162 sqq.
semet immeavit, dedit etiam carni
CHRISTOLOGICAL PERICHORESIS 183
tur," says the Council of Ephesus (431), " carnem Domini viznficatricem esse et propriam ipsiiis Verhi Dei Patris sed z'elut alterius praeter ipsum coniuncti eidem per dignita- tem ant quasi divinam habentis habitationem, ac non po- tius vivHicatricem esse, quia facta est propria Verbi cuncta vivificare valentis,^^ anathema sit." ^^
3. The Import of Perichoresis. — The doc- trine of Perichoresis contains the most effec- tive and trenchant refutation of all Christological as well as Trinitarian heresies. It categorically excludes Nestorianism and Adoptionism, which assert that the two natures co-exist side by side, and it disproves Monophysitism and Monotheli- tism, because the mutual in-existence of the two natures necessarily supposes their respective in- tegrity. Thus there can be no exaggeration of the notion of unity, which would result in real confusion. Perichoresis represents the golden mean between heretical extremes and is equally effective against Nestorius and Eutyches. Im- plying as it does the truth that there are in Christ two natures, a divine and a human, it strikes effectively at all those heresies which deny either the Divinity or the humanity of our Lord and Saviour. Pope Leo the Great gives apt expression to this thought when he says : "Tot a enim est in
11 ffdpKa ^woiroiov . . . 5rt ye- 12 Denzinger-Bannwart, Enchiri-
yove idia rov Aoyov rod ra ttavTO. dion, n. 123. Cfr. Petavius, De In- fwo^oyei;' IffxvovTos, earn., X, i sqq.
i84 UNITY IN DUALITY
maiestate humilitas, tota in hmnilitate maiestas, nee infert unitas eonfusionem, nee dirimit propri- etas unitatem." ^^
ARTICLE 2
THE COMMUNICATION OF IDIOMS