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.