If our bodies exist in space and time, subject to the laws of physics, our minds must be somehow hidden within them like strange immaterial `Ghosts in the Machine`. Introspection may give us direct access to our own mental world, but we can never know much about other people`s. Such views have been regarded as common sense since Descartes, argues Gilbert Ryle, but they are based on a disastrous `category-mistake`. This epoch-making book cuts through confused thinking and forces us to re-examine many cherished ideas about knowledge, imagination, consciousness and the intellect. The result is a classic example of philosophy in action.