Ideas have spurred the way to human progress, from the earliest cave dweller to the latest frontiers of computers and technology. This is a human-scale distillation of the 2500 ideas which have had the greatest impact on our development through the ages. It includes a huge variety of terms including the intimidating, such as post-modernism, structuralism and chaos theory, the unusual, including alchemy, polyphony and parasychology, while familiar terms such as civilization and beauty are explained anew. Aimed at the non-specialist reader, this book is a companion to the vital ideas which have shaped our world.