Sir Peter Medawar, who died recently, was an unusually articulate advocate of the worth of scientific endeavour. He displays skills of argument that should be the envy of any literary essayist, comparable, perhaps, in lucidity, reasoning power and effect, to T.H. Huxley.

Five things strike one about his writings. Firstly, in our century, the great age of science, it should not surprise us that Medawar invokes the vision of Francis Bacon. He has a strong sense of the history of science. Bacon was, with Newton, a god to the Enlightenment; and Medawar is a direct descendant of the Enlightenment tradition of rational humanism - and hope. His essays show how keenly he is aware of a sense of a loss of hope in our own culture; but he is impatient with those who blame an ill-assimilated notion of 'science' for their confusion - impatient, that is, with self-indulgent pessimism. One may not entirely agree with him about the 'Hope of Progress'; or that all pessimism is self-indulgent. But his arguments have to be assimilated and answered; they derive their strength and momentum from a great tradition of thought, for which he is a persuasive spokesman.

It follows, secondly, that his specific discussions of the ideas of Teilhard de Chardin, Koestler, 'existential' psychiatry and other popular misconceptions of twentieth century 'poeticism' are bracing ones. 'Instead of wringing our hands over the Human Predicament, we should attend to those parts of it which are wholly remediable, above all to ...