In Byzantine music the term Octoechos (Gr. ὀκτώ, eight, and [symbol omitted]χος, mode) has two distinct though closely allied meanings. In general it refers to the system of eight modes that forms the compositional framework of Byzantine ecclesiastical music: four authentic and four plagal modes, as in Western chant. More particularly it designates a collection of proper hymns, chiefly for the Morning and Evening Services, providing an entire set of such pieces for each mode. The collection was designed for performance in cycles of eight weeks: in the 1st week (beginning after Easter) the hymns of Mode I Authentic would be used, in the second week the hymns of Mode II Authentic, and so on, until after the completion of the modal series the cycle recommenced with Mode I. Thus the Octoechos, taken in conjunction with the hymns of feasts fixed by the calendar, and those of the Lenten and Easter seasons, made provision for music throughout the church year. In its earlier form it comprised pieces for the Sundays only; later additions supplied hymns for the weekdays as well, the whole compilation receiving the name of Great Octoechos (ἡ μεγάλη Ὀκτώηχος) or Parakletike (Παρακλητική).
Origins. The origins of the system, as of the collection based upon it, are obscure. It appears to owe little if anything directly to the classical and Hellenistic Greek tonal system, despite the assignation of classical names to modes of the Octoechos by some medieval Byzantine theorists. Attempts by modern scholars to trace it to the musical vestiges or cosmological beliefs of earlier Near Eastern peoples are speculative at best. Even the time of its appearance in Christian hymnody cannot be determined with any precision. An 11th-century text of the Plerophoriai of John of Maiuma (c. 515) contains an allusion to "music of the Octoechos," but its authenticity is questionable. Grave doubt attaches also to the oftrepeated assertion that a hymn collection of the same period, the work of severus of antioch (512–19), was an Octoechos. The sole surviving MSS of this collection present it in Syriac translation, and the earliest of these MSS, more than a century and a half later than the presumed original, shows no sign of an arrangement according to mode; only in much later copies does such a categorization exist. In any case it seems that the eight-mode system had become established within the Greek liturgical world by the end of the 7th century. To cite one piece of evidence: a papyrus fragment no later than early 8th century gives a modal sign—though no other musical notation—for the hymns it preserves. Byzantine tradition ascribed the composition of the Octoechos, or at least a large part of its Sunday nucleus, to St. john damascene (c. 750). In its generality the attribution is certainly dubious, but it may contain some element of historical fact. The very earliest musical MSS (10th century) have "John the Monk" as author of the canons of the Octoechos; and the initial letters of another set of Sunday hymns form the word Ἰωάννου (of John)—this sort of acrostic signature is traditional in Byzantine hymnology. But even if the identity of this "John" with the Damascene were assured, whether he was in any sense the composer of the music that the MSS convey would remain doubtful—and this is true generally of the poets to whom hymns are ascribed. In the 9th century, after the resolution of the iconoclastic controversy, the Octoechos was completed by the addition of the weekday hymns, the work of monks of the studion monastery in Constantinople—in particular Joseph the Hymnographer (883). The final canon in the series has as its acrostic τ[symbol omitted]ς Ὀκτωήχου τ[symbol omitted]ς νέας θε[symbol omitted]ον τέλος (the divine conclusion of the New Oktoechos), perhaps the earliest known instance of the term's referring unambiguously to a corpus of hymns. Not until much later does the word occur as heading of a separate MS or section of a MS.
The Modes in Their Technical Aspects. As for the musical system itself, the songs from every particular mode are composed largely from a restricted set of melodic formulas characteristic of that mode. These formulas may be employed in many different combinations and variations; nevertheless, most of the phrases of any given hymn are reducible to one or another of this small number of basic melody-fragments. (For formulas of Mode I as they are exemplified in a selection of phrases from a number of hymns, see E. Wellesz, A History of Byzantine Music and Hymnography [2d ed. Oxford 1961] app. V.)
The church music belonging to various peoples, such as the Serbs, the Armenians, the Syrians, and the Copts, as found in our own times, exhibits analogous modal systems, depending in the same fashion on melodic formulae—the specific formulae, of course, differing from one musical culture to another. (No musical documentation from the Byzantine period exists for any of these peoples; there are, e.g., medieval Armenian musical MSS, but their notation is undecipherable.) Study of these modal systems has led some scholars to conclude that, in such a system, each mode is defined simply by its characteristic melody patterns, rather than by some abstract scale pattern: the latter sort of definition was the subsequent rationalization of theorists. Byzantine theory in its full development did provide such a rationalization; and the system thus defined appears to be essentially identical to that of Latin plainchant. This conclusion is suggested by the medieval Latin practice of assigning Greek number names to the Latin modes; it is confirmed by Wellesz' publication of a hymn whose Greek text had been translated into Latin, and whose music appears substantially the same in both kinds of notation. The total range of the system (with rare extensions) covers what is represented in modern transcription as the two-octave white-key gamut a–a ". Within this, Mode I Authentic has an approximate range of d–d ', with finalis on a ' or d ; Mode II Authentic, e–e ', with finalis on b ' or e ; Mode III Authentic, f–f ', with finalis on c ' or f ; Mode IV Authentic, g–g ', with finalis on d ' or g. The plagal modes have ranges lying a fourth below the numerically corresponding authentic; they use only the lower finalis of the two found in the corresponding authentic modes. This diatonic system remained the basis of Byzantine music down to the 17th and 18th centuries, when it disappeared, along with the entire repertory embodying it, under the Turkish influence, leaving only the texts and the modal assignations as they had been in medieval times. For a categorization of the contents of the Octoechos as a musical servicebook, see Tillyard.
Bibliography: e. wellesz, Eastern Elements in Western Chant (Monumenta Musicae Byzantinae 1; Oxford 1947); "Die Struktur der servischen Oktoëchos," Zeitschrift für Musikwissenschaft 2 (1919) 140–48. h. j. w. tillyard, The Hymns of the Octoechus, 2 v. (Monumenta Musicae Byzantinae 3, 5; Oxford 1940,1952). j. jeannin and j. puyade, "L'Octoëchos syrien," Oriens Christianus NS 3 (1913) 82–104, 277–98. a. baumstark, Festbrevier und Kirchenjahr der syrischen Jakobiten (Paderborn 1910). e.w. brooks, "The Hymns of Severus," Patrologia orientalis, ed. r. graffin and f. nau (Paris 1903–) 6:1–179; 7:593–803. f. nau, "Jean Rufus, évêque de Maïouma: Plérophories," ibid. 8:1–208. l. tardo, L'Ottoeco nei MSS. melurgici (Grottaferrata 1955). Παρακλητικὴ ἤτοι Ὀκτώηχος ἡ μεγάλη (Rome 1885); Ὀκτώηχος (Rome 1886). o. strunk, "The Tonal System of Byzantine Music," Musical Quarterly 28 (1942) 190–204; "The Antiphons of the Oktoechos," Journal of the American Musicological Society 18 (1960) 50–67.