This book addresses the problem of consciosness in a material world. The author argues that a belief in consciousness does not undermine atheistic naturalism, despite the fact that consciousness cannot presently be explained by the physical sciences. He considers subjectivity, intentionality, the limits of introspection, mental causation, and the hidden structure of consciousness. There is also material on philosophical laws, mental kinds, functionalism, and machine consciousness. The book concludes that most of the difficulties that philosophers and scientists have experienced in this area are in essence conceptual ones.