Rethink is the story of how old ideas that were mocked or ignored for centuries are now storming back to the cutting edge of science and technology, and informing the way we lead our lives. It's the story of Grace Hopper, the programming language pioneer who allowed us to speak to computers; of Ignaz Semmelweis, the brilliant doctor who worked out how infections occur long before there was a proper germ theory of disease, and was committed to an asylum for his trouble; of Democritus, the laughing philosopher who inferred the atomic foundations of reality just by thinking about bread. Incorporating examples from areas ranging from epigenetics to value investing, from chess tactics to quantum physics, Rethink shows what we can learn by revisiting old, discarded ideas and considering them from a new perspective. From within the rich anecdotes of bad ideas emerge good ones, helping us find new ways to think about ideas in our own time - from novel proposals in the boardroom to grand projects for social and political change. Armed with this picture of the surprising evolution of ideas and their triumphant second lives, you will see the world differently - and perhaps be better equipped to change it.