Popular welsh hymn written in 1745 by clergyman William Williams who was born in Llandovery in Carmarthenshire. He wrote around 800 hymns. It was translated into English by Peter Williams (no relation) in 1771. It has been re-written several times. It is mostly sung to the tune Cwm Rhondda written by John Hughes from Pontypridd named after the Welsh town - he added 'Cwm' because there was already a tune called 'Rhondda'.