Among the fragments of the Gospel Problems and Solutions of Eusebius is one taken by Angelo Mai, back in the 1820’s, from a then unpublished Sunday Sermon by John Xiphilinus.
Xiphilinus is best known to us as the author of an epitome of Cassius Dio. The epitome of Xiphilinus, together with that of Zonaras, are now all we have for many books of Dio.
But a Sunday sermon? That’s new.
A query to LT-ANTIQ pointed me at the BBLK entry, by Erich Trapp. This reads in English:
John Xiphilinus the Younger, nephew of the patriarch of the same name, also known as a philosopher who lived around 1080 as a monk and Logothetes in Constantinople. He made a name for himself as both a homiletic and historical writer. In the continuation of Symeon Metaphrastes he wrote for the emperor Alexius I Comnenus (1081-1118) a dedicated Menologion for the months of February to August, which is, however, only extant in a Georgian version. Furthermore, there are about 53 sermons (` ‘Eρμηνευτικαὶ διδασκαλίαι) by him on the Sundays of the year, which have been written by the author in a number of manuscripts. He models himself particularly on John Chrysostom. He also wrote on behalf of the Emperor Michael VII Ducas (1071-8) an extract from books 36-80 of Cassius Dio covering the period 68 BC to 229 AD.
Works: Georgian Proemion to the Menologion, ed K. Kekelidse, Christianskij Vostok 1 (1912) 325-347; M. van Esbroeck, La légende “romaine” des SS. Côme et Damien et sa métaphrase géorgienne par Jean Xiphilin, OCP 47 (1981 ) 389-425 and 48 (1982) 29-64; Homilies 1-25 ed. S. Eustratiades, ‘Oμιλίαι εἰς τὰς κυριακὰς τοῡ ἐνιαυτοῡ I, Trieste 1903; Cassius Dio, ed. Boissevain I-V, Berlin 1895-1931.
Lit:: Beck, Kirche 629f. (mit Bibl.); – LThK V (1960)1098 (F. Dölger); – F. Halkin, Le concile de Chalcédoine esquissé par Jean Xiphilin, Rev. ét. byz. byz. 24 (1966) 182-8; – H. Hennephof, Der Kampf um das Prooimion im xiphilinischen Homiliar, Studia byzantina et neohellenica Neerlandica 3 (Leiden 1972) 281-299; – Dict. Spir.VIII (1974) 792f. (D. Stiernon, mit Bibl.); – Der Kleine PaulyV (1975) 1434 (K. Ziegler); – L. Canfora, Xifilino e il libro LX di e Dione Cassio, Klio 60 (1978) 403-7; – P. Brunt, On Historical Fragments and Epitomes, Class. Quart. NS 30 (1980) 477-494.
So it sounds as if 25 of the sermons have been published; not much. A search in COPAC reveals that the PG 120 contains “orations”. But no sign of the Eustratiades edition of sermons. I haven’t been able to find any sign of these.