GILSON, ÉTIENNE (1884–1978), was an educator, lecturer, author, and historian of medieval philosophy. Born in Paris, Gilson was a Christian believer and lifelong promoter and defender of the intellectual life of the church. He treasured his Roman Catholic schooling but discovered his love for philosophy in a secular lycée and at the positivistic Sorbonne. Convinced that before doing philosophy one had to learn what philosophy already existed, he entered upon a career of exact historical study, following the principled method that would mark all his work: to study the original writings of the great thinkers, to understand their thought within its historical context, and to present their teaching objectively.

Under competent Cartesian scholars Gilson concentrated on the modern classics but did his research on the medieval sources used by Descartes. While teaching in the lycées (1907–1913), he completed his dissertation on the...