A sacrament according to St. Thomas Aquinas is "the sign of a sacred thing in so far as it sanctifies men." St Augustine called it "a visible form of an invisible grace."The sacraments are essential to the life of the Church in most traditions but they have received little attention from theologians of late and there is great misunderstanding about their nature and purpose.Fr. Anselm Grnn, the best-selling German Benedictine, has set about answering...