From The Warrior Saints in Byzantine Art and Tradition, published by Ashgate, England 2003.
For Byzantinists, Demetrius is certainly a most fascinating saint and this for several reasons. One is the rich complexity of the source material -literary, archaeological, cultic, iconographical - available about him. By no means all of it has been adequately studied. For example, no critical edition exists of his Passio prima and Passio altera. Also numerous Encomia of the Saint still remain in manuscript. As the late Paul Lemerle remarked, so long as these texts remain unpublished scientifically, no definitive appreciation of the Saint is possible.
Another reason for his fascination is the number of ambiguous aspects of his life and pristine cult. Did he really originate in Sirmium (Sr(ij)emska Mitrovica) or in Thessaloniki? Were relics of him preserved? If so, where were they placed? Did he have a martyrium on the site of which his basilica was constructed? Or was the account of his imprisonment in the calidarium of the baths, repeated, with differences, in both Passions, fabricated in order to explain the emplacement of his shrine?
These are all points on which scholars have emitted differing and conflicting opinions. However, conflict does not end here. The date and stages of the construction of the saint's sanctuary, as well as the repairs effected after the seventh-century fires, are also controversial subjects.
Leaving aside controversy, at least for the moment, certain unusual aspects of the saint's cult must not be neglected. Most outstanding is the fact that, at least in the earliest centuries for which we have records, his devotees congregated around his ciborium, placed near the narthex at the north end of the basilica. Why? Were the saint's relics placed, not inside it, certainly, but perhaps beneath it? At his ciborium, apparently, he tended to perform personal miracles (curing maladies, for instance). Moreover, during these early centuries, the saint's interventions were almost entirely limited to granting favours to citizens of Thessaloniki or to safeguarding the city against marauders. Why did he not, like others -Theodore Tiron, George or Sergius and Bacchus, for example - attract a wider clientele?
Yet another - and probably not the only other - fascinating aspect of the saint is the later development and renewal of his cult as a myroblytos. His myron became notorious, and no doubt contributed largely to his acceptance as a universal saint (in Byzantine and Slav countries, for, unlike St George, he never cut much ice in the West).
It is not my intention to give here a full exposition of the cult and iconography of St Demetrius.(1) Such an exposition would require not only a whole book but also a preliminary study of the many unpublished Encomia already mentioned.(2) My aim is rather to call attention to the specific facets of Demetrius as a military saint - that is to say, to distinguish between the points in which he differs from other members of the celestial army and those points which they have in common.
This study may be divided conveniently into three sections: the original Demetrius; Demetrius the myroblytos; and the later cult of Demetrius among Greeks and Slavs.
1. Some brief expositions do exist: my own 'St Demetrius: The Myroblytos of Thessalonika', Eastern Churches Review 5,1973, pp. 157-78, reprinted in Studies V; R. Janin, 'Demetrio di Tessalonica', BS 4, 558-64; Idem, Les églises et les monastères des grands centres byzantins (reworked by J. Darrouzès), Paris, 1975, pp. 365-72. Subsequently a spate of monographs concerned with aspects of St Demetrius has been published. R. Cormack has also produced a succinct but balanced exposition: 'The Making of a Patron Saint: The Powers of Art and Ritual in Byzantine Thessaloniki', World Art. Themes of Unity in Diversity, ed. I. Lavin, Pennsylvania State University Press, 1989, III, pp. 547-54. Of the numerous encyclopaedia articles, that by R. Aubert, 'Demetrius de Thessalonique', DHGE 14 (1960), 1493-9, is worth retaining.
2. They are listed, when known, BHG, 534-47. See P. Lemerle, Les plus anciens recueils des miracles de saint Demetrius I, Le texte, Paris, 1979, pp. 10-11 (BHG, 449-450). See also Idem, II, Commentaire, Paris, 1981, Appendix, p. 243.