Greek for “gladsome light”, Phos Hilaron is a hymn that was already considered a time-honored tradition over 1,600 years ago.  Functionally, it offers a word of praise while the lamps or candles are lit in a chapel or home for the evening.  Deeper, the lyrics describe the sanctification of time that good liturgy inevitably does: “as we come to the setting of the sun… we sing your praises.”  And yet, God is “worthy at all times to be praised.”  That “happy voices” are appropriate for the worship of God can be a stumbling block – what if the worshiper does not feel happy one day?  The idea of happiness in biblical literature, from which this hymn is certainly derived, is nearly identical with blessedness.  Like Psalm 1:1, “Happy/Blessed is the man…” we also ought to read here – God is worthy to be praised by the voices of God’s blessed people.  We are therefore comforted, also, that even if we do not emotionally feel happy, we know that there is a fundamental happiness, or joy, that we can derive from the blessings of God that we have already received.  This is spelled out with an example in the next line where Jesus is proclaimed as the “Giver of Life”, and celebrated with the final assertion that he is to be glorified “though all the worlds” – that is, saints in heaven and earth alike are united in the worship of the eternal God.

O gladsome light,
pure brightness of the everliving Father in heaven,*
O Jesus Christ, holy and blessed!

Now as we come to the setting of the sun,
and our eyes behold the vesper light,*
we sing your praises, O God: Father, Son, and Holy Spirit.

You are worthy at all times to be praised by happy voices,*
O Son of God, O Giver of Life,
and to be glorified through all the worlds.

This anthem was introduced into the Prayer Book tradition in 1979.  Only one translation change has been made in this version: the “gracious light” has become a “gladsome light.”  It is a lamp-lighting hymn drawn from ancient Christian custom (especially in the Byzantine and Ambrosian rites), being referenced as far back as 379AD by St. Basil the Great.  Several metricized versions of this anthem can be found in Anglican hymnals.

The rubrics permit another hymn or Psalm to be used in its place, acknowledging the Western custom of having a variety of Office Hymns according to the season or occasion.