This hymn can be found on Tradition in Action:
A Solic Ortus Cardine is a devout Latin poem celebrating the birth of Our Lord. With pious reverance and poetic paradox the singer meditates on Our Lord’s Incarnation within the immaculate temple of the Blessed Virgin Mary. At His coming in humility at the manger in Bethlehem Our Lord, who sustains and feeds even the loweliest creature, suffers cold and hunger. He who is the King of Kings and Almighty Creator of all the universe condescends to walk amongst sinful men, living and dying so that we may be redeemed by Him.
A Solic Ortus Cardine is an ancient 5th century poem hymn. It was composed by Coelius Sedulius, and is here sung by the Queen’s College Choir.