Hauntingly Beautiful melodies in the "O magnum mysterium" of Victoria sung by an Academy

This hymn from the Breviary was set to music by many composers. This version is by Tomás Luis de Victoria (Vittoria) a famous composer in 16th-century Spain. He was famous specifically during Counter-Reformation, along with Giovanni Pierluigi da Palestrina and Orlando di Lasso. Victoria was not only a composer, but also an organist and singer as well as a Catholic priest.
  Latin text
O magnum mysterium, et admirabile sacramentum, ut animalia viderent Dominum natum, iacentem in praesepio! Beata Virgo, cujus viscera meruerunt portare Dominum Iesum Christum. Alleluia!
English translation
 O great mystery, and wonderful sacrament, that animals should see the new-born Lord, lying in a manger! Blessed is the Virgin whose womb was worthy to bear our Saviour, Jesus Christ. Alleluia!