Hymn #1: Immortal, Invisible, God Only Wise
This hymn’s tune, ST. DENIO, known in Wales as JOANNA, was based on an old folk melody traditionally sung with words about a cuckoo. It was modified and first used as a hymn tune by John Roberts in his Canaidaeth y Cysegr (1839). St. Denio is the Latin form of St. Dennis.
Many Welsh hymn tunes originated from folk songs or ballads that were already familiar in secular settings. These typically strong tunes adapted well to hymn texts and are often memorable in their predictable structure. ST. DENIO was first used with this text in The English Hymnal (1906) – a pairing that has proved widely successful for a century.

