Few theories have been more misunderstood – by both advocates and opponents – than the Natural Law. To become meaningful in the living context of human affairs, it must be freed from the inhibiting associations of mere speculation. Here is a brilliant statement of the traditional position – with all its limitations clearly delineated – and a cogent presentation of modern objections to the customary formulation. These analyses by a philosopher, a political scientist, a lawyer, a doctor and an anthropologist demonstrate convincingly how “principles” must be rooted in the existent situation of man as he lives in a changing world. As Illtud Evans, O.P., says in his Introduction: “The purpose of this symposium is not to establish any theory of the natural law, still less to demolish its classical expression. It is simply an attempt to submit the traditional doctrine to the scrutiny of those who are concerned not so much with a mere intellectual exercise as with the use that is made of a concept in the living context of human affairs. When St Thomas remarks that ‘what is false to nature is false from every point of view’ he is perhaps reminding us that those who use the word ‘Natural” have a special obligation to be scrupulously concerned with the human implications of what they say”.