This thesis is focused upon the double treatise of Theodoret of Cyrus written before the
Council of Ephesus (431) entitled On the Holy and Vivifying Trinity and On the Incarnation/Inhumanation of the Lord . After a brief presentation of Theodoret's life and the place of
this work in his oeuvre (Ch. 1), Ch. 2 is concerned with the textual tradition, including the
time of writing, the handing down through history in various manuscripts, the ascription to
Cyril of Alexandria, the editions and the restoration to the author by modern scholarship.
Chapters 3 and 4 are concerned with the doctrinal analysis of the first and the second half
respectively. Apart from the presentation of the theological issues discussed by the author,
during which various Trinitarian and Christological concepts and expressions as well as
some soteriological and pastoral emphases (including their effect upon Theodoret's
Christology) are analysed, the thesis is also an attempt to vindicate the author from some
one-time and modern charges concerning his alleged crypto-Nestorianism. During the
exegesis and historical-theological commentary it will be argued that some of the main
accusations brought against him (i.e. the absence of a genuine communicatio idiomatum, a
two-subject Christology, the non-application of a hypostatic union in Christ around 431 etc.)
when compared to the valid theological standards of his own time (The Formula of
Reunion, Leo's Tome and the Chalcedonense) — are largely unwarranted or anachronistic.
Although some - verbal - defects of Theodoref s way of expressing his concept of the union
in Christ remain (defects which he himself corrected in his later works), nevertheless his
basic concept and model ofthe Word Incarnate is theologically sound.
The final conclusion of the work is that the understanding of Chalcedonian orthodoxy
according to either of the two ancient parallel traditions is admissible. The key figures of the
two schools -Cyril and Theodoret - are to be seen as presenting two aspects of the same
truth. Although their emphases are different, the Alexandrian and Antiochene Christological
systems represent rather complementary than opposing views and the rejection of either
would result in a partial but significant loss of our common Chalcedonian heritage.
Since no critical edition is yet available, all the quotations found by modern scholars are
listed in the Appendix, including my own textual discovery of a few longer excerpts from the
virtually unquoted first tract. Thus, among the purposes of the thesis is also the intention to
contribute towards the first critical edition of this double treatise. The Appendix also contains
the first English translation of both halves.