‘ Williams of Pantycelyn ’ was the chief hymn-writer of the Methodist awakening in Wales , and much of the success of Welsh Methodism must be attributed to the popularity of his hymns. These were published in books and tracts in the following order: Aleluia (in six parts between 1744 and 1747 , and in one volume in 1749 ); Hosanna i Fab Dafydd (in two parts, 1751 and 1754 , and an English collection, Hosannah to the Son of David , 1759 ); Rhai Hymnau a Chaniadau Duwiol , 1759 ; Caniadau … y Môr o Wydr , 1762 (with reprints in 1763 , 1764 , and 1773 ); Ffarwel Weledig (in three parts, 1763 , 1766 , and 1769 , and in one volume under the title Haleluia Drachefn , c. 1790 ; Gloria in Excelsis (in two parts, 1771 and 1772 , together with an English collection of the same name, 1772 ); Ychydig Hymnau , 1774 ; and Rhai Hymnau Newyddion (three little collections in 1781 , 1782 , and 1787 ). These hymns were important not only from the point of view of the nation's religious life but as a valuable contribution to its literary culture.

He also wrote two long poems: Golwg ar Deyrnas Crist , 1756 (2nd imp. 1764 ), and Bywyd a Marwolaeth Theomemphus , 1764 (2nd imp. 1781 ). The first of these poems is an attempt to evaluate the divine purpose in the creation, while the second is a study of the soul's progress in the world and of the various experiences which befall it. He wrote about twenty-eight elegies, some of them very ordinary, while others — such as those upon Lewis Lewis , Grace Price , Howel Harris , and Daniel Rowland — occasionally reached a high standard. He published a number of prose books: Llythyr Martha Philopur , 1762 , and Atteb Philo-Evangelius , 1763 ; Crocodil Afon yr Aipht , 1767 ; Tri Wyr o Sodom — a kind of novel, 1768 ; Liber Miscellaneorum , 1773 ; Ductor Naptiarum: Neue Gyfarwyddwr Priodas , 1777 ; Templum Experientia, Apertum , 1777 ; and Pantheologia, Neu Hanes Holl Grefyddau'r Byd — a laborious work published in parts between 1762 and 1779 . There is no room here to list his translations from English , or the lesser books and tracts which he wrote in prose and verse. Between 1744 and 1791 his name appears on nearly ninety books and booklets, and this will give some indication of the extent of his literary labours. He is remembered today because of his hymns, but recently fresh interest has been taken in his poetry as a whole, as well as in his prose. He was the first romantic poet in Wales and, as such, he exercised considerable influence not only on his contemporaries but on his successors.