This book explores the character of the Eucharist as communion in and through sacrifice. It will stimulate discussion because of its controversial critique of the dominant paradigm for Eucharistic theology, its reclamation of St. Thomas Aquinas' theology of the Eucharist, and its response to Pope John Paul II's "Ecclesia de Eucharistia". This book argues that the Eucharist cannot be separated from sacrifice, and rediscovers the biblical connections between sacrifice and communion. It is timed to coincide with the Year of the Eucharist, proclaimed by Pope John Paul II. It reclaims the riches of St. Thomas Aquinas' theology of the Eucharist, which had recently been reduced to a metaphysical defense of transubstantiation.