The most obvious illustrations of the way our world has shrunk in the twentieth century are cosmonauts in orbit, the diffusion of news by mass media, the missiles threatening targets thousands of miles and a quarter of an hour distant from their launching sites. Yet in a world where time and distance have dwindled so dramatically most men remain wholly preoccupied by personal and local affairs alone. This narrowness of outlook amidst the pressures of modern living and the constant threat of nuclear war produces a dangerously outdated and limited view of the world which is faced with the crucial choice between international integration or global destruction. This challenge to all men is doubly a challenge to Christians. Canon Leclercq stresses, however, the need to distinguish between "statistical" Christianity and the fully committed Christians who recognize their heavy responsibility to act as a leaven within the world, to work actively towards the achievement of unity among mankind. Canon Leclercq faces the facts of life in the contemporary world without evasion or easy optimism, discussing war, patriotism, international tensions with a realistic assessment there as obstacles to world integration.