A canon is a structured hymn used in a number of Eastern Orthodox services. It consists of nine odes, sometimes called canticles or songs depending on the translation, based on compositions (also called odes) found in the Bible and with one exception, the Old Testament.
The canon dates from the 7th century and was either devised or introduced into the Greek language by St. Andrew of Crete, whose penitential Great Canon is still used on certain occasions during Great Lent. It was further developed in the 8th century by Sts. John of Damascus and Cosmas of Jerusalem, and in the 9th century by Sts. Joseph the Hymnographer and Theophanes the Branded.
Over time the canon came to replace the kontakion, a vestigal form of which is still used on several occasions and which has been incorporated into the performance of the canon.
As with all other Orthodox church music, a canon is sung by a choir or cantor in a cappella chant. An ode of the canon is begun by singing the Biblical ode from its beginning. At some point this is interrupted by an introductory stanza called an irmos, "link", which poetically connects it to the subject of the canon. Following the irmos and sung alternately with the subsequent verses of the ode are a series hymns comprising a single stanza each, or troparia, set in the same melody and meter as the irmos, that expand on its theme. The ode is completed with a final stanza called katavasia, which might or might not be present depending on the service and occasion, and which also varies accordingly. It might be a repetition of the irmos, the irmos of the second canon when more than one canon is being sung together, the irmos of the canon for an upcoming major feast day, or some other verse prescribed by the service books. (Katavasia means "coming down" and the verse is so called because as originally performed the two choirs would descend from their places on the left and right sides of the church to sing it together in the middle.)
When a full canon is performed, between odes three and four a sedalen or "sitting hymn" is sung. Between odes six and seven a vestigal kontakion is sung with only its prooimion, or initial stanza, and the oikos or first strophe. This order is rearranged somewhat if the canon is accompanied by an akathist.
In modern practice the Biblical odes are not actually sung except during Matins on the weekdays of Great Lent. Most often odes one through nine are all sung with the exception of ode two; there are therefore only eight odes sung in most canons. Ode two has an extremely penitential theme, so this too is only sung during Lenten weekday Matins. At these times the services call for the singing of three odes only. (The book containing the changeable portions of services for Lent is called the ''Triodion'' in consequence.) Because of this, canons that are not sung at this time often have no irmoi or troparia of ode two recorded for them. Ode two is also sung in the Great Canon of St. Andrew.
Instead, the ode normally begins with the irmos. The troparia that follow are each introduced by a brief refrain which is again determined by the subject of the canon. For example, in a Canon of the Resurrection the refrain is, "Glory, O Lord, to thy holy Resurrection"; in a Canon to the Most Holy Theotokos the refrain is, "Most Holy Theotokos, save us"; and in the most general case it is "Glory to thee our God, glory to thee." For the last one or two troparia, the refrain is replaced by the doxology "Glory to the Father, and to the Son, and to the Holy Spirit both now and ever and unto the ages of ages. Amen." However, during Sunday Matins the Magnificat, which forms half of the ninth Biblical ode, is usually sung in its entirety before the irmos.
The total number of troparia is determined by local usage. Theoretically there are as many as fourteen for each ode with some troparia repeated if the service books do not prescribe enough of them and some conjoined if there are too many. This makes the canon too lengthy for typical parish use, so more often no more than three troparia are sung regardless of how many troparia or canons are prescribed.
Although it is intended that the troparia be sung this is impractical in most cases, so it is usually done only during the Matins of Pascha. They are most often read recto tono by a single reader as are the refrains that precede them. Often two readers will read the refrains and troparia anitphonally.
Canons are used most notably at Matins, but also at the Midnight Office for Sunday; at Great and Small Compline; and at special services such as the Paraclesis and those of similar structure such as the Panakhida or Molieben. In the latter cases it is often vestigal, consisting of no more than a selection of irmoi with refrains and doxology. Canons may also be used in private prayer either as a regular part of a rule or for special needs. One traditional prayerful preparation for reception of the Eucharist is to read three canons and an akathist the evening prior. When used privately there is generally no attempt at an elaborated musical or metrical performance.
Poetic and musical structure
The Biblical odes are not identical in meter, and so although all the music is performed in the same mode each ode must comprise an individual composition. However, in the original Greek compostitions, the irmos and troparia would by design be of the same meter and so could use the same melody. Acrostics would often be present as well, read down a canon's troparia, and sometimes involving the irmos as well if it was composed at the same time. The meter and acrostic would be given along with the canon's title.
The nine odes may be found in any complete Orthodox Psalter, and they are:
- The Ode of Moses in Exodus (Exodus 15:1-19)
- The Ode of Moses in Deuteronomy (Deuteronomy 32:1-43)
- The Prayer of Anna the mother of Samuel the Prophet (1 Kings 2:1-10)
- The Prayer of Habakkuk the Prophet (Habakkuk 3:2-19)
- The Prayer of Isaiah the Prophet (Isaiah 26:9-20)
- The Prayer of Jonah the Prophet (Jonah 2:3-10)
- The Prayer of the Three Holy Children (Daniel 3:26-56)*
- The Song of the Three Holy Children (The Benedicte, Daniel 3:57-88)*
- The Song of the Theotokos (The Magnificat, Luke 1:46-55) and the Prayer of Zacharias the father of the Forerunner (The Benedictus, Luke 1:68-79)
Collections of irmoi for various occasions are found in the Irmologion, one of the standard service books of the Orthodox Church. Irmoi and troparia for the canons are also found in the Menaion and the Octoechos, and in the seasonal service books the Triodion and the Pentecostarion.