ZEOON. — In the Byzantine liturgy, this term denotes the hot water which, after being blessed by the priest, the deacon pours into the chalice immediately after the *immistio*, while the priest says: «Fervour of faith, filled with the Holy Spirit».
This rite, which exists only in the Byzantine liturgy, is neither universally practised nor strictly obligatory, and is still observed today according to the norm of canon 33, attributed to Patriarch Nicephorus I (806–15). The priest must not celebrate the liturgy without hot water unless in case of necessity or when it is impossible to obtain it (F. Pitra, *Iuris eccles*..., vol. II, Rome 1868, p. 330). At the Council of Florence the Greeks were questioned about the rite of the *zeoon*, but their reply has not come down to us.
At the Ruthenian Synod of Zamoscia (1720) this rite was abolished, but it was retained in the *Ecologia* of Benedict XIV (1754) and restored, under certain conditions, in the Ruthenian recension of the *Liturgicam* of Rome (1942).
In the present formula, the *zeoon* has a subjective meaning, symbolising the fervour of the faithful’s faith and of the Holy Spirit, whereas in the formula prior to the 15th century the meaning was objective: the fervour of the Holy Spirit. The blessing formula speaks of the fervour of the saints, and Nicholas Cabasilas sees in the rite the descent of the Holy Spirit upon the Church, a commemoration fittingly placed at the conclusion of all the mysteries of Redemption recalled in this sacrifice (cf. S. Salaville, *Cabasilas, Explication de la divine Liturgie*, Paris 1943, pp. 206–10). But for Simeon of Thessalonica the rite signifies that the dead body of the Lord remained life-giving, because it was not separated from the divinity nor from the energies of the Holy Spirit, and since heat signifies life, those who receive the Precious Blood, as it were, touch the life-giving side of the Lord (PG 155, 741). This latter moralising intention regarding Holy Communion is held by modern Greek authors. While A. Baumstark traces the rite back to ancient table customs (*Byzant. Neugriech. Jahrb.*, 15 [1939], p. 237) and J. Brinktrine to a simple blessing (*Ein auffallender Brauch der byzant. Mesliturgie*, in *Theol. und Glaube*, 1937, pp. 637–43), L. H. Grondijs, in a thorough but often unreliable study (*L'iconographie byzant. du Crucifié mort sur la Croix*, 2nd ed., Brussels 1947), links it with the doctrine of the incorruptibility of Christ’s Body—a doctrine falsely accepted for a time by the imprudent Justinian, at whose epoch the rite would have originated—and renews the more orthodox interpretation of the mystics of the Studion monastery in the 11th century (Nicetas Stethatos), perpetuated by Balsamon (PG 137, 619), by Simeon of Thessalonica and others, and illustrated from the 12th century onward with the image of Christ crucified with the lance-wound from which living blood and hot water gush forth.
The first historical document attesting the rite of the *zeoon* is the reply of the Armenian katholikos Moses (574–604; PG 132, 1248–49; better, G. Garitte, *La Narrazione de rebus Armeniae*, Louvain 1952, pp. 243–44). On the other hand, the account of John of Nikiu (H. Zotenberg, *Chronique de Jean de Nikiu*, Paris 1883, pp. 413–15) and that of the anonymous *Life of Theodore Sykestos* (Theophilus Ioannou, *Μνημεῖα ἀγιολογικὰ*, Venice 1884, p. 460) are irrelevant. Thus, after the 6th century there is a complete silence until the canon of Patriarch Nicephorus, while in liturgical documents the first mention of the rite is found in the 12th-century version by Leo Thuscus.