FOR centuries the sages have been telling us how to live well; preachers, moralists, political theorists, economists—all have poured out an unbroken stream of exhortation and advice. And yet most of us still find it very hard. Nowadays, however, the medical aspect of life occupies more and more important a place in people's thoughts, and it is from this point of view that Professor Greenwood will address his good counsel in this talk.