I. In treating of the dogma of the Divine

Trinity we based our exposition upon the ''Atha- nasian Creed." ^ According to this same eccle- siastical symbol we will also divide the treatise on Christology, treating ( i ) of '"Duality in Unity," ^ or the constitutive elements of Christ, and (2) of "Unity in Duality," or the Hypostatic Union.^
The significant parallel between the two dogmatic treatises seems to point to an analogical relation between their respective subjects. Such a relation does indeed exist. Both treatises are concerned with transcendental mysteries which revolve about the concepts of " Na- ture " and " Hypostasis," and their mutual relations.
It would not, however, be correct to conclude from this analogy tliat Christ, in respect of the relation of Nature to Person, is a perfect image of the Trinity. There is a very essential distinction. In the Blessed Trinity one Divine Nature subsists in three divine Hy- postases (or Persons), who possess a real and identical nature in common; whereas in Christ two distinct and complete natures, one divine, the other human, sub- sist in one Hypostasis, t. e., the Divine Person of the Logos. Or, to put it somewhat differently, the Blessed
1 Cfr. Pohle-Preuss, The Divine 3 Unitas in dualitate, unto hypo- Trinity, pp. 5 sqq. staiica.
2 Dualitas in unitate.
4 INTRODUCTION
Trinity forms a real Trinity of Persons in an absolute Unity of Nature, whereas in Christ there is a duality of Natures in an absolute Unity of Person.
This twofold element in the constitution of the God- man is clearly stated in the " Athanasian Creed " : "Est ergo fides recta, ut credamus et coniiteamur, quia Dominus noster lesus Christus Dei Filius, Deus et homo est.^ Deus est ex substantia Patris ante saecula genitus, et homo est ex substantia Wratris in saeculo natus: per- fectus Deus, perfectus homo, ex anima rationali et hu- mana came subsistens, aequalis Patri secundum divini- tatem, m,inor Patre secundum humanitatem. Qui licet Deus sit et homo, non duo tamen, sed unus est Christus; ** unus autem non conversione divinitatis in carnem, sed assumptione humanitatis in Deum, unus oninino non con- fusione substantiae, sed unitate personae." Anglice : " For the right faith is that we believe and confess that our Lord Jesus Christ, the Son of God, is God and Man ; God, of the Substance of the Father, begotten before the worlds ; and Man, of the substance of His mother, born in the world; perfect God, and perfect Man: of a rea- sonable soul and human flesh subsisting; equal to the Father, as touching His Godhead : and inferior to the Father, as touching His Manhood. Who although He be God and Man: yet He is not two, but one Christ; one ; not by conversion of the Godhead into flesh : but by taking of the Manhood into God; one altogether; not by confusion of substance : but by unity of Person." *
ADualitas in unitate. 191 1, n. 40. For brevity's sake
B Unitas in dualitate, we shall hereafter cite this work
6 Enchiridion Symbolorum, Defini- as Denzinger-Bannwart, Enchiri-
tionum et Declarationum de Rebus dion. Our translation of the Atha-
Fidei et Morum Auctore Henrico nasian Creed is that of the Eng-
Densinger. Editio undecima, Enten- lish Book of Common Prayer. We
data et Aucta, quam paravit Clemens quote verbatim, literatim et puna-
Dannxeart, S. J., Friburgi Brisgoviae tatim from the Oxford edition of
INTRODUCTION 5
2. Defining the essential constitution of man in our treatise on Dogmatic Anthropology^ we answered two questions, viz.: (i) How many- constitutive elements are there in man? and (2) How are these elements united? We ascer- tained by the light of Divine Revelation that there is in man a real ''duality in unity," in as much as he is composed of a material body essen- tially informed by a spiritual soul.
Similarly, though not in precisely the same sense, we may ask: (i) What is the number of constitutive elements in Christ? and (2) How are these elements united?
Revelation answers these two questions thus: (i) There are two constitutive elements in Christ, a divine nature and a human nature; and (2) these two natures are united hypo- statically. The "Athanasian Creed" points out this analogy when it says : "For as the reasona- ble soul and flesh is one man : so God and Man is one Christ." *
According to Cardinal Franzelin the dogma of the In- carnation may be most effectively expounded from the following points of view:^ (i) Who assumed human nature? (2) What did the Son of God assume? (3)
1834. Cfr. Pohle-Preuss, God: His S " Nam sicut anima rationalis et
Knowability, Essence, and Attri- caro unus est homo, ita Deus et
bvtes, p. 318, note 6. homo unus est Christus."
7 See Pohle-Preuss, God the Ah- 9 Cfr. Franzelin, De Verbo In-
thor of Nature and the Supernat- carnato, thes. i, 4th ed., Rome 1910, ural, pp. 124 sqq.
6 INTRODUCTION
How are Divinity and humanity united in Christ? (4) Why did the Son of God hypostatically assume a human nature? The answer to the first question (quisf) is: The Divine Logos. The answer to the second question (quid f) is: A real and genuine human nature. The an- swer to the third question (quomodof) is: Godhead and manhood are hypostatically united in Christ. The answer to the fourth question (ad quid?) is: The Son of God assumed flesh in order to redeem the human race.
Of these questions the first three alone belong to Chris- tology proper ; the fourth finds its place in Soteriology.
The division we have chosen coincides materially, though not formally, with that suggested by Cardinal Franzelin. The only diflFerence is that we base our expo- sition on the " Athanasian Creed." Our reasons for so doing are purely didactic. The concept " duality in unity " contains the reply to the questions quisf and quid?, while the answer to quomodof is supplied by the concept of " unity in duality."
It may be objected that the so-called Athanasian Creed is not the work of St. Athanasius and lacks the authority of a primitive symbol. We reply that, though " of Western origin and . . . composed (probably) during the fifth century in Southern Gaul," ^° this symbol is " an admirable resume of the doctrine of Athanasius. ... In the West it was recited at Prime since the ninth century, was used by the clergy in giving popular instruction as a summary of Christian doctrine, and was held in particular esteem as a basis and criterion of ecclesiastical faith."" Dr. Kiinstle holds ^^ that the
10 Its authorship is variously at- ogy, p. 255, Freiburg and St. Louis tributcd to Honoratus of Aries, 1908.
Eusebius of Vercelli, and Vincent 12 Antipriscilliana, pp. 204 sqq.,
of Lerins, Freiburg 1905.
11 Bardenhewer-Shahan, Patrol-
INTRODUCTION 7
Athanasian Creed was written in Spain against Priscil- lianism, while H. Brewer ^^ attributes it to St. Ambrose.
We now enter upon the treatment of Christology ac- cording to the division already indicated, vis.: (i) Duality in Unity, or the Constitutive Elements of Christ, and (2) Unity in Duality, or the Hypostatic Union of the two Natures in Christ.
General Readings : — Among the Fathers : Athanasius, De In- carnatione Verbi (Migne, P.G., XXV, 95 sqq., 938 sqq. ).—* Cyril of Alexandria (Migne, P.G., LXXV, LXXVI).— Leontius, Adv. Nest, et Eutych. (Migne, P.G., LXXXVI, 1267 sqq.).— Maximus Confessor (Mi&ne, P.O., XC, XCI).— The teaching of these writers is summarized by St. John Damascene, De Fide Ortho- dox a, I. Ill (Migne, P.O.. XCIV).— On the teaching of Theo- doret see A. Bertram, Theodoreti Episcopi Cyrensis Doctrina Christologica, Hildesheim 1883.— On the doctrine of St. Cyril, cfr. A. Rehrmann, Die Christologie des hi. Cyrillus von Alexan- drien, Hildesheim 1902.
The student may also consult with profit St. Augustine's En- chiridion (Migne, P.L., XC; English translation by J. F. Shaw, in Vol. IX of The Works of Aurelius Augustine, Bishop of Hippo, 3rd ed., Edinburgh 1892) ; St. Ambrose, De Incarnat. Dominicae Sacram. (Migne, P.L., XVI, 817 sqq.), and Fulgentius, De In- carnatione Filii Dei (Migne, P.L., LXV).
Among the Schoolmen : * St. Thomas, S. TheoL, 3a, qu. i- 26 (summarized in Freddi-Sullivan, Jesus Christ the Word In- carnate, Considerations Gathered from the Works of the An- gelic Doctor St. Thomas Aquinas, St. Louis 1904; A. Vonier, O. S. B., The Personality of Christ, London 1915 ("a very unconventional rendering of the most important points of the third part of the Summa." Preface, p. vi).— *Idem, Contr. Gent., IV, 27 sqq. (Rickaby, Of God and His Creatures, pp. 359 sqq., London 1905). — Billuart, De Incarnatione, t V, ed. Lequette. — Salmanticenses, De Incarn., Vols. 13-16, ed. Paris 1870 sq. — Suarez, De Incarn., Lugd. 1592. — *Bellarmine, De Christo, t. I, ed. Vives, Paris 1870. — *De Lugo, De Mysterio Incarna- tionis, t. II, III, ed. Vives, Paris 1890-92. — Gregory of Valentia, De Incarn. Divini Verbi, Venice 1600. — *Ysambert, De Mysterio Incarnationis, Paris 1639. — Wirceburgenses (Holtzclau, S. J.),
13 Das sogenannte Athanasianische Glaubetubekenntnis ein Werk des hi. Ambrosius, Faderborn 1909.
8 INTRODUCTION
De Incarn. Verbi, Vol. VI, ed. Paris 1879. — Legrand, Tract, de Incarn. Verbi Divini (Migne, Cursus Compl., t. IX, Paris i860).
— Fr. I. Bertieri, De Verbo Dei Incarnato, Vindob. 1773. Among later theological writers : Bautz, Einig. B. Jungmann,
Heinrich, Hurter, Hunter, van Noort, in their respective text- books.— Also *Franzelin, De Verbo Incarnato, ed. 6, Romae 1910. — *F. A. Stentrup, De Verbo Incarnato, I: Christologia, 2 vols., Oeniponte 1882. — *L. Billot, De Verbo Incarnato, ed. 5, Romae 1912. — Chr. Pesch, Praelect. Dogmat., t. IV, ed. 3, Fri- burgi 1909. — G. B. Tepe, Instit. TheoL, Vol. Ill, Paris 1896. — *L. Janssens, De Deo-Homine, I: Christologia, Friburgi 1901.
— C. V. Schazler, Das Dogma von der Menschwerdung Gottes, Freiburg 1870. — Oswald, Die Erlosiing in Christo Jesu, 2 vols., 2nd ed., Paderborn 1887. — Scheeben, Dogmatik, Vols. II and III, Freiburg 1878 sq. (summarized in Wilhelm-Scannell, A Manual of Catholic Theology Based on Scheeben' s " Dogmatik," Vol. II, pp. 45 sqq., 2nd ed., London 1901). — Idem, Die Mysterien des Christentums, 3d ed., Freiburg 1912. — H. P. Liddon, The Di- vinity of Our Lord and Saviour Jesus Christ (Bampton Lec- tures) London, Oxford, and Cambridge 1867. — E. C. Minjard, L' Homme-Dieu, 2 vols., Paris 189S-99. — I. Souben, Le Verbe Incarne, Paris 1902. — E. Krebs, Der Logos als Heiland im ersten Jahrhundert, Freiburg 1910. — Cfr. also W. Drum, art. " Incarna- tion " in Vol. VII of the Catholic Encyclopedia.
On the history of the dogma, consult *Schwane, Dogmenge- schichte. Vols. I and II, 2nd ed., Freiburg 1892-95. — *J. Bach, Dogmengeschichte des Mittelalters vom christologischen Stand- punkte, 2 vols., Vienna 1873-75. — H. Kihn, Patrologie, 2 vols., Paderborn 1904-08. — J. Tixeront, History of Dogmas, Vol. I. English ed., St. Louis 1911; Vol. II, 1914; Vol. Ill, 1916.— B. J. Otten, S. J., A Manual of the History of Dogmas, Vol. I, St. Louis 1917. pp. 45 sqq., 76 sqq., 127, 146, 150, 154 sq., 165, 171, 195, 221, 249 sqq., 308 sqq., 388 sq., 408 sqq., 435 sqq.; Vol. II (1918), pp. 171 sqq.. 497 sq.
Against Modernism: M. Lepin, S. S., Christ and the Gospel, or Jesus the Messiah and Son of God, Engl, tr., Philadelphia 1910.
— M. E. Mangenot, Christologie, Commentaire des Propositions XXVII-XXXVIII du Decret du Saint-Office " Lamentabili," Paris 1910.
On theChristological teaching of St. Paul, cfr. F. Prat, S. J., La Thiologie de Saint Paul, Vol. II, pp. 165-243, Paris 1912.