An anthem for SATB choir and organ, based on the translation by John Keble (1792-1866) of the third century Greek hymn "Phos Hilarion".

This ancient hymn is about "gladdening light", in particular the light of Jesus Christ who comes from God the Father into our dark world. It is intended to be sung in the evening. What is unusual about the hymn is the position of its doxology ("Father, Son and Holy Ghost") in the middle of the hymn, rather than after the last verse, as is common in most settings of psalms, canticles and many hymns from the last 200 years. This enables it to retain a biblical freshness, in which the Son of God is the main focus of attention, with theological reflection secondary to the primary reality that he is the "giver of life".

The musical setting is here based around a major seventh chord, and it uses deliberately chromatic harmonies, both of which illustrate the words with sparkle and colour. The first verse is sung by soprano and alto soloists, and its words are then repeated by the whole choir a cappella. After a shortened, quiet second verse, with its reflective doxology, the organ performs a brief, noisy and celebratory cadenza, before launching into the final verse with the full choir in exuberant praise. The anthem ends, as it started, with the phrase "gladdening Light" extending as if to the furthest ends of the world.