Iolo Morganwg (or Morgannwg in modern spelling; pronounced [ˈjolo morˈganːug] was the bardic name of Edward Williams (Llancarfan, Glamorgan, Wales 1747-1826), an influential antiquarian, poet, collector and literary forger.[citation needed] The name is Welsh for "Ned of Glamorgan". Like many Romantic poets he was addicted to laudanum for most of his life, which may have affected his mental condition. Among his writings was Cyfrinach Beirdd Ynys Prydain, or "The Mystery of the Bards of the Isle of Britain" (1829), a treatise on Welsh metrics. He also forged an extra set of Welsh Triads.