Petros Bereketis () or Peter the Sweet (Πέτρος ο Γλυκής) was one of the most innovative musicians of 17th-century Constantinople (Ottoman period). He, together with Panagiotes the New Chrysaphes, Balasios the Priest and Germanos Bishop of New Patras was one of the most influential figures in the evolution of the Byzantine psaltic art following the fall of Constantinople in 1453, although he never was associated with the Patriarchate in Fener. For many years, he served as the protopsaltis (first cantor) of church St. Constantine of the Hypsomatheia (Samatya) quarter close to the Marmara coast. During his lifetime, which is approximately supposed to be between 1665 and 1725, while Chrysanthos mentioned that he served there in the time of the Archon Protopsaltis at the Great Church of Christ of Panagiotis Halatzoglou and his Lampadarios John Trapezountios (1727-1748). Education Nothing is known about his real life time, so that Gregorios Stathis assumed that there was a confusion between Petros Bereketis, John Trapezountios' student Petros Peloponnesios and the latter's follower Petros Byzantios. Petros Bereketis began his musical studies in his home city of Constantinople, but later visited Mount Athos for a considerable length of time to study under the noted teacher of Constantinopolitan musicians, the Moldavian Monk Damian of Vatopedi (1650-1720). Compositions The surviving compositional corpus left by Bereketis is extensive, spanning works across all ecclesiastical genres including communion chants (koinonika for both Sundays and weekdays), asmatic doxologies, cherubic hymns, kratemata, pasapnoaria, polyelea, doxastica and katavasies for various feast days. Among the more notable of his compositions is the eight-mode setting of "O Theotokos and Virgin" for two alternating choirs, most commonly chanted in all-night vigils on Mount Athos. Heirmoi kalophonikoi In particular, his musical settings of the heirmoi (unsurpassed both in quality and in quantity by his contemporaries) gave rise to a style of paraliturgical chant that came to be known as the kalophonic heirmological style, named for a certain method of melodic thesis which referred to the Old Heirmologion, but in a soloistic and rather deliberate way characterised as kalophonic ("beautifully sounding") melos. With respect to Petros' exceptional talent which he mainly developed in the genre of kalophonic heirmos, he is sometimes referred to as the "father of kalophonic heirmoi," although the genre existed since Byzantine times and it had already been revived by Balasios and some other contemporary composers like Germanos. Petros in fact got acquainted to this genre during