Octave species various available intervals could be combined in any order, even restricting species to just the diatonic genus would result in twelve ways of dividing the octave (and his 17th-century editor, Marcus Meibom, pointed out that the actual number is 21), but "only seven species or forms are melodic and symphonic" . Those octave species that cannot be mapped onto the system are therefore rejected . In chant theory beginning in the 9th century, the "New Exposition" of the composite treatise called "Alia musica" developed an eightfold modal system from the seven diatonic octave species of ancient Greek theory, transmitted to
Octave (liturgy) Season make up the octave of Easter and are celebrated as solemnities of the Lord, with proper readings and prayers. Since 30 April 2000, the "Second Sunday of Easter", which concludes the Easter Octave, has also been called Divine Mercy Sunday. The Christmas Octave is arranged as follows: Among the Eastern Orthodox and Byzantine Rite Eastern Catholic Churches, what in the West would be called an Octave is referred to as an Afterfeast. The celebration of the Great Feasts of the church year are extended for a number days, depending upon the particular Feast. Each day of an Afterfeast will