Colin S. Morrison is a science graduate, writer and freelance philosopher who is an expert in consciousness studies. He gained his honours degree in theoretical physics at the University of St Andrews in the 1990s, and currently lives in the UK, where he teaches mathematics. He has studied the mind and the difficulties of explaining subjective experience for twenty years, presented at high-profile international conferences, and discussed his ideas with the world's leading philosophers. He is now confident he has found the only scientifically defensible solution to the mind-body problem. Unlike all previous theories of consciousness, his proposal - Position Selecting Interactionism - explains the image-forming capability of our experiences purely as a product of natural selection acting upon ordinary matter. It invokes no substances, forces or principles that are not implied by successful scientific theories. And most interestingly, it requires none of the strange functionalism to which other theories attribute the astonishing appropriateness in the way particular types of experience represent particular types of data (pain for damage, unpleasant emotions for detrimental circumstances, pleasant feelings for beneficial circumstances, and so on). But what really makes his theory stand out from all the rest is that it provides a full explanation of what experiences are. He never brushes them aside as 'illusions' or 'an issue that will disappear when we have fully understood how the brain works'. His theory explains exactly what they are and what they have evolved to do. It tells us precisely what role they play in the workings of the human brain. And it shows us how and why they acquired that role. He has previously published parts of this theory in abbreviated form in the Toward a Science of Consciousness program book for the years 2010, 2011, 2012 and 2014, and in The Science of Consciousness 2016 program book, all published by the University of Arizona Centre for Consciousness Studies. However, the present work is ground-breaking as it is the first full-length account of this theory. It is the first publication that brings all the arguments that support it together in one place, and shows why this author believes it to be far superior to all the many other theories of consciousness that have to date been advocated in the philosophical literature.