Book excerpt: Richard Gregory was one of the major scientific thinkers of our time. Originally published in 1986, here he presents essays on the rich subject of perception. How we experience colours, shapes, sounds, touches, tickles, tastes and smells is a mysterious and rich inquiry. Wonderful as these sensations are, though, he argues that perception becomes really interesting when we consider how objects are identified and located in space and time as things we interact with, using our intelligence to understand them. Gregory’s essays convey the crucial importance of the major scientists and their achievements in the study of perception; but they also show us how much we can learn from our surroundings, our language, our times, our successes and our failures. Why are we so often fooled, in scientific as well as everyday life?