Geoffrey 's major work is his Historia Regum Britanniae which appeared at the beginning of 1136 . Between 1136 and 1148 he supervised four ‘editions’ of it and it is probable that he made minor changes from time to time. One of these ‘editions’ is dedicated to Robert , earl of Gloucester (q.v.) ; in another the dedication is to Robert and Waleran de Beaumont , count of Mellent (or Meulan) ; in yet another the work is presented to king Stephen and to Robert ; while the fourth appeared without a dedication. The ‘ Prophecies of Merlin ’ appear in the body of the Historia (book VII according to the arrangement of later editors) and this section is dedicated to Alexander , bishop of Lincoln ( Oxford was within the diocese of Lincoln ). It is certain that this section had appeared independently between 1134-5 , because Ordericus Vitalis quotes from it in his Historia Ecclesiastica ( 1135 ). The Historia Regum Britanniae is divided into six sections (or twelve books according to the editors) in which Geoffrey gives the ‘history’ of the Britons from the coming of Brutus to the arrival of the Saxons ; but it is evident that the author did not set out to extol the deeds of the Britons of Wales . Geoffrey states that his chief source was ‘a very ancient book’ ( ‘quendam britannici sermonis librum vestustissimum’ ) given to him by Walter ; no trace of this book has been discovered. It is more certain that he has drawn on Gildas , Nennius , and Bede in addition to the early genealogies. The Bible , patristic writings, and Latin authors (e.g. Vergil , Juvenal , Lucan , Sallust , and Ovid ) were some of his other sources. The work also shows the influence of the various romances and Geoffrey has made use of local traditions. The Historia immediately became widely popular; there are about 200 extant manuscripts, nearly fifty of them written in the 12th cent. , but all the manuscripts have not yet been fully collated.
The Historia brought king Arthur (q.v.) into a new and greater fame, and the ‘matter of Britain’ was presented to the world. A Welsh version of the Historia appeared fairly soon as ‘ Ystoria Brenhinedd y Brytaniaid ’ or ‘ Brut y Brenhinedd .’ It is believed that three different persons translated the work into Welsh , each in his own way. There are extant nine copies earlier than the end of the 14th cent. ; e.g. the ‘ Dingestow Brut ’ ( N.L.W. MS. 5266 ) belongs to about 1300 , but it is based on a version written early in the 13th cent. There is another version in the ‘ Red Book of Hergest .’
The Historia was first printed by Badius Ascanius at Paris in 1508 with Ivo Cavellatus as editor ; other editions appeared in 1517 and 1587 (the latter by Jerome Commelin at Heidelberg ). A definitive critical edition of the work has not yet been published. Between 1148 and 1150 Geoffrey composed his ‘ Vita Merlini ,’ a Latin hexameter poem of 1528 lines dedicated to Robert de Chesney , bishop of Lincoln .
Professor Idris Llewelyn Foster, M.A., F.S.A., (1911-84), Oxford
Published date: 1959