The renowned historian Christopher Dawson devoted his long and brilliant career to precisely the kind of historical research of which theologians and churchmen stand in great need, particularly if they are to meet the authentic demands of the ecumenical era. Dawson's book traces the formation of Christian culture from its roots in the Judeo-Christian tradition through the rise and the decline of medieval Christendom. Here, as in all his works, he sees religion as the dynamic element of culture. He shares with Arnold Toynbee the ideal of a universal spiritual society as the goal of history; but whereas Dr. Toynbee sees this as to be achieved by a consensus of the great world religions, East and West, Dawson sees it as coming from the working out of the Catholic principle. "Catholicism does not rest on the consensus of human wisdom--even on its highest and most spiritual plane--but on a divine revelation which is also an act of creation." The Church is, in his view, just such a society working as a leaven in history; its role in history is that of healing the divisions of humanity by bringing back the nations into spiritual unity. This work by Dawson has all the qualities which have earned him international acclaim as an historian and as a Christian Humanist.