An enigmatic hymn for saint Petka-Paraskeva: The canon and its interpretation in the thematic replacement of chants

In MS Lavra E-10 / Z-58 from the 17th c. there is a sticheron ωdesnuju Spasa predsta devo in plagal second mode (sixth mode) for the service in honour of St. Petka-Paraskeva (14 October). Such a hymn cannot be found in other manuscripts or printed editions in the service for St Petka. This chant is a unique hymnographical artefact which is a good example of the literary atmosphere of the early Balkan revival and of an ancient liturgical chant practice - the thematic replacement of chants.