MY choice of subject may seem surprising. I have written about poets and novelists and men of action; never about research-workers. That in itself was a good reason for doing so. In an age when science is transforming human life for better or for worse, it is natural that we should take an interest in the scientist, in the way his mind works, in the nature of his investigations.

But why Fleming? I might answer, plausibly enough, that the importance of his discovery was sufficiently great to determine my choice. As it turns out, however, the initial decision was not mine at all. In November 1955 I received a letter from Lady Fleming in which she said that she very much wanted me to write a life of her husband, who had died in the early part of that year. The suggestion excited me and I replied that I was prepared to discuss it.

Lady Fleming came to see me in Paris. Being, herself, a doctor and a bacteriologist, she was able to explain very exactly the nature of the problems with which I should have to deal. She promised to make her husband's papers available to me. But, persuasive though she was and tempted though I felt to try my hand on so unfamiliar a subject, I was still uncertain about my ability to do what she wanted and asked for more time in which to think over the proposal.

There were good reasons for my hesitation. For one thing, a scientist, I thought, would produce a far better book than I could hope to and, for another, the character of Fleming, a silent and secretive man, would be difficult to portray. But difficulty is itself a challenge and I felt eager to accept it. Several French friends — Professor Robert Debre and Professor Georges Portmann, who had known Fleming, as well as Dr Albert Delaunay of the Pasteur Institute, who promised to instruct me in such bacteriological knowledge as I should need — were encouraging.

I began my literary career as a young man with The Silences of Colonel Bramble, a taciturn Scot. There would, I felt, be a certain satisfying intellectual symmetry about writing, in my old age, The Silences of Professor Fleming. The two men had much the same virtues, though in different forms. The mixture of quiet humour, of loyalty and independence, of reserve and intelligence, were precisely what I found attractive. To cut a long story short, I said 'yes*.

I do not regret my decision. By studying at close range the methods and the way of life of those who are engaged in scientific research, I have learned a great deal. But there is more to it than that. I very soon realized that there was no lack of human drama in an existence which on the surface appeared to be remarkably uniform. The relationship between Fleming and his master, Almroth Wright, contained a number of dramatic elements. To live in a laboratory is to be one of a group, and this life I have done my best to describe. As to my hero, the better I got to know him, the more attractive did I find him.

I should never have been able to collect the necessary evidence and documentary material but for the unwearying and generous help given to me by Lady Fleming. Thanks to her, I was able, on my visits to London, to meet almost all those — scientists, doctors and friends — who had played a part in Fleming's career. Among them I was surprised and delighted to renew acquaintance with Dr G. W. B. James to whom the 'Dr O'Grady' of my first book owed so many of his paradoxical and brilliant ideas. The threads of which our lives are woven sometimes cross in the most unexpected, strange and helpful manner.

To mention by name all those who have been so kind as to tell me, to write to me, or otherwise to record their memories, would make too long a list. They will be found mentioned in the course of this book wherever I have occasion to quote from them. Let me here express the gratitude I feel. First and foremost I wish to thank Lady Fleming, but for whom this book would never have been written; and, next in order, Mr Robert Fleming, Sir Alexander's brother, who has provided me with many invaluable details of his early life. I am no less beholden to Dr Albert Delaunay who not only undertook, with great patience, my instruction in a field of knowledge which for me was strange and difficult, but also read more than once my manuscript and proofs. Finally I owe a debt to Professor Cruickshank who, as Fleming's successor as Director of the Wright-Fleming Institute, has done me the honour of writing the Introduction to this volume.

A. M.