NICEPHORUS CALLISTUS XANTHOPULUS. — Little information is available about the life of this Byzantine ecclesiastical writer. From chronological indications, some vague and others precise, which are found in his works, whether printed or in manuscript, it can be reasonably inferred that he lived approximately from 1256 to 1335. He was a priest in the church of Hagia Sophia in Constantinople (Cod. Miscell. gr. 79, in the Bodleian Library, Oxford, and PG 145, 609 C) and later became a monk under the name of Nilus (Cod. Vat. Reg. Succ. 182, f. 1).
Works. — A complete and definitive list of the works of N. C. is premature; the known works can be classified as follows:
1. Historical writings
The work that immortalized N. C. is his *Ecclesiastica Historia* (PG 145, 559; 146; 147, 1-448) in 18 books. It begins with the origins of Christianity and ends with the death of Phocas (610). The first letter of each book forms the acrostic Νικηφόρου Κωνσταντίου. From the dedication to Emperor Andronicus II Palaeologus (1282-1328), one can discern N. C.’s theological stance regarding the Latins (PG 145, 592). The historical value of this work is highly uneven; the assessment depends on the discovery of the sources he used. He also left a catalogue of the bishops and patriarchs of Constantinople: *Enarratio de episcopis Byzantii* (PG 147, 449-68); a short poem *De excidio Hierusalem* (PG 147, 601); a life of St. Nicholas of Myra, etc.2. Liturgical writings
The following are known: a) The *Triodion*, in which he explains the origin and arrangement of the principal feasts of the Triodion in the liturgical calendar (Venice 1639 and 1650); the additional *Pentecostarion* is of doubtful authenticity; b) an *Ermeneia* or explanation of liturgical terms; c) a commentary (*Exegesis*) on the *Anabathmoi* of the eight tones: εἰς τοὺς ἀναβαθμους τῶν ὀκτῶ (Cod. Miscell. gr. 79, f. 5); d) another commentary on the hymn of the troparion of St. Cosmas the Melodist to the Virgin: Ἐξήγησις εἰς τὴν τιμωτέραν, etc. (Cod. Miscell. gr. 79, f. 181, and Cod. gr. Roe 3, f. 131, in the Bodleian Library, Oxford); e) a metrical summary of the *Triodion* in iambic verse (the 3-2-6 were published by Athanasiadis, *Ἐρμηνεία εἰς τοὺς ἀναβαθμους τῆς ὀκτῶ ἤχου παρὰ τοῦ Νικηφόρου Καλλίστου τοῦ Ἐκκλησιοῦ* (Jerusalem 1862), critically defective).3. Exegetical writings
On Holy Scripture, N. C. left a *Synopsis of Divine Scripture* (PG 147, 607-24) and a metrical summary of Jewish history from the time of the Maccabees: *Synoptike pros Theian Graphen* (ibid., 623-32).The *Ecclesiastical History* of N. C. was published in Latin by J. Lange at Basel in 1555 (not 1553); in French in 1567;
NICETAS BYZANTIUS, also called φιλόσοφος and διδάσκαλος. — A few years younger than Patriarch Photius, he flourished in the second half of the 9th century.
N., whose life remains unknown, was a brilliant dialectician and polemicist, as shown by his treatises against the Muslims: *Refutation of the Book of Mohammed* and *Two Epistles of the Agarenes to Emperor Michael III*; against the Armenians: *Refutation of the Letter of the King of Armenia*; against the Latins: *Capita syllogistica XXIV*. This last pamphlet, edited by S. Pissidios, *Βιβλίον καλούμενον 'Pavntiμοῦ Στηλέως* (Leipzig 1758, pp. 230-48), was republished by J. Hergenröther, *Monumenta graeca ad Photium eiusque historiam pertinentia* (Regensburg 1869, pp. 84-138); the others are found in PG 105, 588-684.