For thousands of years, humans and their innovations have shaped our history. But some inventions and discoveries are so profound, they not only change the course of history, they also manage to leave a legacy so powerful, it can be called world-changing. This book looks at 10 of these ideas - from the invention of the wheel which brought about a radical change in travel, craftsmanship and manufacture, to anaesthetics, which ushered in a new era of medical care.