Phos Hilaron () is an ancient Christian hymn originally written in Koine Greek. Often referred to in the Western Church by its Latin title Lumen Hilare, it has been translated into English as O Gladsome Light. It is the earliest known Christian hymn recorded outside of the Bible that is still in use today. The hymn is part of vespers in the Byzantine Rite and the Catholic Church, and also included in some Anglican and Lutheran liturgies. Origins The hymn was first recorded by an unknown author in the Apostolic Constitutions, which was written in the late 3rd or early 4th century. It is found in a collection of songs to be sung in the morning, in the evening, before meals, and at candle lighting. Phos Hilaron is to be sung at the lighting of lamps in the evening and so is sometimes known as the “Lamp-lighting Hymn”. Despite some of the words to the other three songs being from Scripture or in one case dated to around 150, Phos Hilaron is the first to be considered an actual hymn in the modern sense. It is certainly the first complete example. It is far more rhythmic than the others and is divided into twelve verses varying between five, six, eight, nine, ten and eleven syllables a verse. Basil of Caesarea (329–379) spoke of the singing of the Phos Hilaron as a cherished tradition of the church, the hymn being already considered old in his day (though some attribute the composition of the song to Basil himself). The original melody, as used by the Greek Orthodox Church in the original text, is considered taxing on the voice as it spans almost two octaves, with the voice peaking on the words “Heavenly” and “the Father” (see word painting). At that time in Jerusalem, a lamp was kept perpetually burning in the empty tomb of Christ, its glow a symbol of the living light of Jesus. As Christians gathered to worship the hymn was sung and, in a tradition known as the lighting of the lamps, a candle lit from the lamp was brought forth from the tomb, its bright, solitary flame calling the church to celebrate the Risen Lord. Saint Athenogenes, a saint of unknown date but whose saint's day is 16 July, is believed by some (including Basil) to have composed this hymn on the way to being martyred. He is