In the fields I know best, among the life sciences, it is required that the most expert and sophisticated minds be capable of changing course - often with a great lurch - every few years.

Well, biology today as I see it has an amiable look - quite different from the 19th-century view that the whole arrangement of nature is hostile, 'red in tooth and claw.' That came about because people misread Darwin's 'survival of the fittest.'

Good applied science in medicine, as in physics, requires a high degree of certainty about the basic facts at hand, and especially about their meaning, and we have not yet reached this point for most of medicine.

There's really no such thing as the agony of dying. I'm quite sure that pain is shut off at the moment of death. You see, something happens when the body knows it's about to go. Peptide hormones are released by cells in the hypothalamus and pituitary gland. Endorphins. They attach themselves to the cells responsible for feeling pain.

Some of the shrewdest insight into natural processes have been greeted at the outset by the exclamation 'But that's ridiculous'.

It is a distortion, with something profoundly disloyal about it, to picture the human being as a teetering, fallible contraption, always needing, watching and patching, always on the verge of flapping to pieces.

We are at our human finest, dancing with our minds, when there are more choices than two. Sometimes there are ten, even twenty different ways to go, all but one bound to be wrong, and the richness of the selection in such situations can lift us onto totally new ground.