theologian and spiritual writer. About 1120 he was elected Abbot of the Benedictine abbey of St-Thierry, near Reims. He formed a close friendship with St Bernard, and in 1135 he resigned his abbacy and joined a group of Cistercians who were establishing a house at Signy in the Ardennes.
William's early works were largely didactic and include a treatise in which he tried to synthesize the teaching of the E. and W. Fathers on the relation of the body and the soul. In 1138 he wrote to Bernard urging him to refute Peter Abelard's views on the Trinity and Redemption. He himself wrote against Abelard and against William of Conches. His other works include two commentaries on the Song of Songs, his Meditativae Orationes, and his famous Epistola ad Fratres de Monte Dei de Vita Solitaria, known as the ‘Golden Letter’ and often attributed to Bernard.