Alan Turing: The Enigma by Andrew Hodges

inspired his mother to a whimsical pencil sketch. And although intended as a joke against his dreamy passivity, there might have been a truth in the observation. For something new had happened.
    At the end of 1922, some unknown benefactor had given him a book, called Natural Wonders Every Child Should Know . 8 Alan told his mother later that this book had opened his eyes to science. Indeed, it must have been the first time that he became conscious that such a kind of knowledge as ‘science’ existed. But more than that, it opened the book of life. If anything at all can be said to have influenced him, it was this book which, like so many new things, came from the United States.
    The book had first appeared in 1912 and its author, Edwin Tenney Brewster, had described it as
     
… the first attempt to set before young readers some knowledge of certain loosely related but very modern topics, commonly grouped together under the name, General Physiology. It is, in short, an attempt to lead children of eight or ten, first to ask and then to answer, the question: What have I in common with other living things, and how do I differ from them? Incidentally, in addition, Ihave attempted to provide a foundation on which a perplexed but serious-minded parent can himself base an answer to several puzzling questions which all children ask – most especially to that most difficult of them all: By what process of becoming did I myself finally appear in this world?
    In other words, it was about sex and science, starting off with ‘How the Chicken got inside the Egg’, rambling through ‘Some Other Sorts of Eggs’ until arriving at ‘What Little Boys and Girls are Made Of’. Brewster quoted ‘the old nursery rhyme’ and said that:
     
It has this much truth in it, that little boys and little girls are far from being alike, and it isn’t worth while trying to make either one over into the other.
    The precise nature of this difference was not revealed, and only after a skilful diversion on to the subject of the eggs of starfish and sea-urchins did Brewster eventually arrive back at the human body:
     
So we are not built like a cement or a wooden house, but like a brick one. We are made of little living bricks. When we grow it is because these living bricks divide into half bricks, and then grow into whole ones again. But how they find out when and where to grow fast, and when and where to grow slowly, and when and where not to grow at all, is precisely what nobody has yet made the smallest beginning at finding out.
    The process of biological growth was the principal scientific theme of E.T. Brewster’s book. Yet science had no explanations, only descriptions. In fact on 1 October 1911, when Alan Turing’s ‘living bricks’ were first dividing and redividing, Professor D’Arcy Thompson was telling the British Association that ‘the ultimate problems of biology are as inscrutable as of old.’
    But equally inscrutable, Natural Wonders conspicuously failed to describe where the first cell in the human process came from, only dropping the elusive hint that ‘the egg itself arose by the splitting of still another cell which, of course, was part of the parent’s body.’ The secret was left for the ‘perplexed but serious-minded parent’ to explain. Mrs Turing’s way of dealing with the thorny topic was, in fact, highly consonant with Brewster’s, for John at least was the recipient at Hazelhurst of a special letter starting with the birds and the bees, and ending with instructions ‘not to go off the rails’. Presumably Alan was informed in the same way.
    In other ways, however, Natural Wonders was indeed ‘very modern’, and certainly no little ‘nature book’. It conveyed the idea that there had to be a reason for the way things were, and that the reason came not from God but from science. Long passages explained why little boys liked throwing things and little girls liked babies, and derived from the pattern of the