Fantasia Tertii Toni 'A solis ortus cardine'

Albert de Klerk dedicated his "Octo Fantasiae super themata gregoriana" to the German organist Anton Heiller. These are eight fantasias on Gregorian themes. I recorded the third fantasia on the hymn 'A solis ortus cardine'.

"A solis ortus cardine" is a poem by Coelius Sedulius (died c. 450), recounting Christ's life from his birth to his resurrection. The first seven verses, with a doxology verse by a different writer, were used from the early Middle Ages onwards as a Christmas hymn. Its 23 verses each begin with a consecutive letter of the Latin alphabet, making the poem an abecedarius. It is one of the oldest parts of the Roman Catholic liturgy, with two hymns formed from the first seven and four later verses. There have been monastic translations into Anglo-Saxon and later translations into other languages, most notably the German versification of Martin Luther during the Reformation. Luther translated the first seven verses into 'Christum wir sollen loben schon'.
(source: Wikipedia)