born 0441; 1100, England
died 0441; 1169, Étoile, near Poitiers, Aquitaine
Monk, philosopher, and theologian.
Isaac joined the Cistercians during the reforms carried out by St. Bernard de Clairvaux . His scholarly works make use of logical argumentation and are influenced by the Neoplatonism of St. Augustine . His principal work, Letter to Alcher on the Soul (1162), integrates Aristotelian and Neoplatonic psychological theories with Christian mysticism. A leader of humanism in his day, he suggests that the intellect enables humans to grasp eternal ideas in time and that intelligence allows humans to intuit the reality of God.