This collection of Professor MacKinnon's writings shows his three preoccupations: philosophical, theological, and ethical. As a philosopher and theologian working in one of the world's great scientific centers, Professor MacKinnon is aware (as he says) "that it is in the laboratories of the molecular biological research unit and in the radio astronomical observatory rather than in the libraries and lecture rooms of the Divinity School that the frontiers of human knowledge are being pushed back." Faced with this challenge Professor MacKinnon's mind is continuously moving on the borderlands between theology and knowledge and is again and again driven to formulate some estimate of the person of Jesus Christ."If I remain in some sense a Christian," he says, "it is because of the questions set to me by the person of Christ . . . we face the question of the sense in which a concrete individual may not simply teach or reveal what is true, as Jesus did to the Samaritan woman and to others, but be the Truth!"These essays are evidence of a powerful and incisive mind which is able to relate the philosophical, theological, and ethical problems of our time and to offer guidance to the serious reader and thinker. Professor MacKinnon is at work on the frontiers where theological and Christian belief is being tested and tried today by the sweep of new knowledge and new disciplines.