Great Canon of St. Andrew, Bishop of Crete

 

The Great Canon of St. Andrew of Crete is the longest canon and is only read in church during the first four nights of Great Lent (Clean Monday through Clean Thursday) and at Matins for Thursday of the fifth week of Great Lent. The canon is a dialog between St. Andrew and his soul. The ongoing theme is an urgent exhortation to change one's life.

A canon is an ancient liturgical hymn, with a very strict format. It consists of a variable number of parts, each called an "ode". Most canons have eight odes, numbered from one to nine, with ode 2 being omitted. The most penitential canons have all nine odes. Some canons have only three odes, such as many of the canons in the "Triodion" (which means "Three Odes").

An "irmos" begins each ode. This is generally sung, and each irmos has a reference to one of the nine biblical canticles, which are selections from the Old and New Testament. A variable number of "troparia" follow, which are short hymns about the subject of the canons. These are usually chanted, not sung. After each troparion a "refrain" is chanted. At the end of each ode, another hymn, called the "katavasia" either the irmos previously sung, or one like it is sung. (Orthodox.net)

Here is a good site for The Who's Who of the Canon of St.Andrew

http://www.pravmir.com/the-whos-who-of-the-great-canon.../