DIACONICON (Διακονικόν), DIACONICO. – ART. – A small room, often apsidal, found in basilican churches beside the apse, on the side opposite the prothesis.
The practice seems to have come from the East, particularly from Syria, where many elements of Christian basilicas were developed and where it is already found in pagan buildings; it is frequent in the churches of Ravenna, but rarer in the Roman region, where it is found only in S. Maria Antiqua, in S. Sinforosa, and in the basilica of Pammachius at Porto. It also served as a treasury, for the safekeeping of sacred vessels and relics.
BIBL.: H. Leclercq, Diaconicum, in DACL, IV, cols. 733–734; P. Toesca, Storia dell'arte italiana. Il Medioevo, Turin 1927, passim. Mario Zocca
LITURGY. — The term is used in several senses. It signifies: 1° the liturgical book of the Byzantine rite containing the litanies or supplications and the prayers recited by the deacon during the various ecclesiastical offices (L. Allatius, De libris et rebus ecclesiasticis Graecorum, diss. I, Paris 1646, p. 97); 2° the supplications themselves, which, in addition to the names ἐκτενὴς εἰρηνικὰ, are also called διακονικὰ. For example: τὰ διακονικὰ τῶν φωτιζομένων (supplications for those being illumined during Lent [*Eucologio, Rome 1873, p. 121]); 3° the place where the deacons are situated. This place is the area in front of the principal door of the sanctuary, where the deacon recites the supplications in the name of the people: Ἀρχεται ὁ διάκονος ἐν τῷ διακονικῷ, ἐν εἰρήνῃ etc. (J. Morinus, De sacris Ordinationibus, Paris 1655, p. 104); but above all, the place where the deacons once prepared the bread and wine destined for the Sacrifice. Situated to the right of the sanctuary, it was later used to store vestments and sacred vessels, liturgical books, etc. It is the sacristy of the Eastern Churches (J. Goar, Εὐχολόγιον, sive Rituale Graecorum*, Venice 1730, p. 13). Placido de Meester