Nearly thirty years ago I wrote the first edition of Microbes and Man. It was an attempt to introduce educated readers, not necessarily scientists, to the world of microbes, and to survey the impact of these creatures on Mankind's economy and society. The book was a quiet success, I am happy to say: it has been translated into several languages and, because the study of microbes continues to advance in fascinating directions, this is its third major revision.

Microbes have a truly enormous influence on people's lives. They clean up the environment and they make soil fertile; they are allimportant in food technology; they make vitamins within our bodies. They can live peacefully within, around and upon us, and some even protect us from other, harmful, microbes, Yet most people are hardly aware that they exist – until a microbial misfortune happens: perhaps a disease breaks out, some food is spoiled, or some valuable or treasured material is found to have rotted or otherwise deteriorated. Only then do most people remember microbes – so it is hardly surprising that they are widely regarded as nasty; invisible enemies that are to be feared or resented.

In my book I wished to change the microbe's unfortunate public image. Of course, it is true that some microbes, especially certain bacteria and viruses, cause illnesses; of course, too, microbes exist which spoil food and attack non-living material – even damaging such improbable objects as concrete and iron pipes. But most microbes are beneficial. Their value to the food, chemical and pharmaceutical industries is (I hope) well-known to students, and perhaps, since the flowering of genetic engineering, to a minority of laymen.