William of Saint Thierry wrote The Mirror of Faith and The Enigma of Faith shortly after he read the Theology of Peter Abelard. Writing at the cistercian abbey of Signy, which he entered in 1135 after fifteen years as a benedictine abbot, he tried to correct what he considered Abelard's failure to root his theology in the faith revealed by Christ in Scripture and explained by generations of Church Fathers. Unless we choose to believe, he was convinced, we will never understand rationally or love truly the triune God who calls us to the full 'recognition which is mutual to the Father and Sone[and] is the very unity of both, the Holy Spirit'.
