Liturgy is at the heart of Christian renewal. But what is at the heart of liturgy? The preoccupation with changing forms of worship over the past few years has tended to obscure what these forms were supposed to liberate: Christ living among us. The content of the Mass is now becoming familiar to all who participate in it. Therefore it is opportune and urgent to develop a theology of the eucharist based upon this content. 'His Presence in the World' is a significant contribution to this vital area of theology. Dr. Lash develops his concept of a dynamic eucharist - a living, acting Christ - in a careful and scholarly manner. He builds on tradition, and in the spirit of the Vatican Council shows how new theology comes from old and fulfills and clarifies what has always been taught. The historical perspective is linked with responsible prophecy to create a relevant theology. Nicholas Lash, born in 1934, is Norris-Hulse Professor Emeritus of Divinity at the University of Cambridge, where he occupied that chair from 1978 until his retirement in 1999. He is the author of some fourteen books and four hundred essays and papers. He was, for eighteen years, a member of the central directorate of the international Roman Catholic journal, 'Concilium', and is a founding member and past president of the Catholic Theological Association of Great Britain. A volume of his sermons is due to be published in London in 2005, by Darton Longman and Todd, who will also publish a volume of his essays in 2006. He is married, with one son, and continues to live in Cambridge.