Oktōēchos is the name of the eight mode system used for the composition of religious chant in Byzantine, Syriac, Armenian, Georgian, Latin and Slavic churches since the Middle Ages. In a modified form
Intonations (ἐνηχήματα) for the echoi plagios devteros, varys, and plagios tetartos listed in a 17th-century Papadike treatise—the intonations are followed by chant incipits (GB-Lbl Ms. Harley 5544, fol. 8r)
Simple Psalmody according to the first section of the Anastasimatarion of Chrysaphes the New dedicated to the echos protos—a 17th-century redaction between Papadic and modern use (GB-Lbl Ms. Harley 5544, fol. 13r)
Papadike—Koukouzelian Tree and its Use for Parallage (D-Tu Codex Chrysander, p. 15)
Papadike—κανώνιον καὶ ἡ παραλλαγή τοῦ Γαβρϊὴλ from the manuscript GR-AOh Ms. 53, fol. 3.
Oktōēchos or Octoechos is the name of the eight mode system used for the composition of religious chant in most Christian churches during the Middle Ages. In a modified form, the octoechos is still re
Papadic Octoechos
…of monodic Orthodox chant today. Until 1204 neither the Hagia Sophia nor any other cathedral of the Byzantine Empire did abandon its habits, and the Hagiopolitan eight mode system came into use not earlier than in the mixed rite of Constantinople, after the patriarchate and the court had returned from their exile in Nikaia in…
Intonation according to Erotapokriseis and standard intonation of echos protos: "You descend 4 steps [φοναὶ] from the echos protos [kyrios protos/authentic protus] and you will find again the plagios protos, this way"
Intonation according to Erotapokriseis and standard intonation of echos devteros: "You do the same way in echos devteros. If you descend 4 steps to find its plagios, i.e. πλ β', thus"
The earliest tonary: the fragment of Saint-Riquier in the Psalter of Charlemagne (F-Pn lat. Ms. 13159, fol. 167r)
The intonation formulas for the 8 tones according to the Aquitanian tonary of Adémar de Chabannes (F-Pn lat. Ms. 909, fol. 251r-254r)