Claude Shannon's theory of information is one of the most important discoveries of the 20th century, up there with general relativity and the structure of DNA for things that reshaped the world. But the man himself was oddly self-effacing, an undoubted genius who cared little for the trappings of academic prestige and power, and who spent the latter part of his life tinkering with odd one-off devices while his disciples invented the practical applications of computing. A Mind at Play is a great biography of an unconventional past.

Shannon was born and raised in upstate Michigan, and was a strong if not top performing student. A chance fellowship for graduate work at MIT put him in contact with Vannevar Bush, and Bush's rooms of analogue computing machinery. Shannon had a magicians touch with devices, and more importantly the ability to see through the complexities of a problem to an underlying mathematics. Shannon was the first to apply a previously obscure branch of formal logic, Boolean operators, to electrical circuits, turning circuit design from an art to a science. Bush pushed him to do a PhD in genetics, where Shannon's equations for the evolution of traits in populations were far ahead of the field, and then saw him to a position at Bell Labs.

Shannon worked on military projects involving automatic gunsights and cryptography, was briefly married, and spent his evenings enjoying jazz and working on a private project on the fundamental nature of communication. His paper, when published in 1948, was like a starting gun, providing a formal basis for the new technology of computers which had been kick-started by the second World War.

Having created a field, Shannon entered a playful semi-retirement. He became a professor at MIT and worked on problems of interest, including a mechanical mouse that 'learned', a chess AI, wearable computers, and juggling and unicycles. By nature shy, he had little interest in leverage his intellectual authority for power and empire building, or even anything like a coherent research plan. He worked on what was interesting, and have advice to colleagues and students by asking provocative questions. Shannon life was made better by his wife Betty, a formidable mathematician in her own right, and children. He was diagnosed with Alzheimer's in 1983, and lived until 2001, in what can only be described as a pitiful shadow of his abilities.

A Mind at Play is a good, loving biography of a subject, whom for all his genius, had a clear purity. But the reason why I didn't give it five stars is that it seems clear that Shannon's tinkering was a clear mode of thought for him, and that his work at Bell Labs provided the impetus for information theory, and for whatever reason, this book fails to convey the joy of thinking with your hands.