St Augustine suggested that hymn singing is “praying twice”: praying with words but also by the actual physical act of drawing deeper breaths and stretching for higher (or lower!) notes that singing entails.
Obvious examples of this are where familiar prayers are set to music – e.g. the Lord’s Prayer (StF 762 and 763); the prayer of St Richard of Chichester, “Day by day, dear Lord” (StF 444); and the prayer attributed to St Francis of Assisi, “Make me a channel of your peace” (StF 707).
However, song itself is a form of prayer – a way of communicating directly with God – and this is described in a number of hymn texts. In “Holy, holy, holy, Lord God Almighty!” (StF 11), the singing of praise to God is an activity undertaken by all kinds of beings and offered out of a world of different contexts. “Early in the morning our song shall rise to thee”, writes Reginald Heber, echoing scenes from the Revelation of St John (4: 8-11). The saints adore God, heavenly creatures join in the worship, and “all they works shall praise thy name in earth and sky and sea”.
Sung prayer (particularly prayers of adoration) is seen as a universal activity. For that reason, St Francis of Assisi (StF 99) invites “all creatures of our God and King” to “lift up your voice and with us sing, / alleluia, alleluia!”