It is by no means fortuitous that our contemporary world is deeply occupied with the problem of time. The literature which has gathered about this problem is not only abundant but also notable for the ways in which various disciplines have sought to wrestle with it. The natural scientist, the philosopher, the theologian, the historian, the sociologist, the poet, and the writer of fiction and drama have all engaged in a common encounter with the mystery of this basic givenness of our human existence. Yet, while it is true that periods like our own incite reflection on time's meaning, the problem plays a role in the history of human thought quite beyond that of the pressures and hazards of eras of social crisis.