Originally published in 1965. For hundreds of years the thinking of philosophers, psychologists, and theologians on the problem of the mind’s relation to the body was dominated by the Cartesian notion that mind and matter are distinct substances. That Descartes also held that there is a union of mind and matter, in a person, has largely been ignored. This may be because, as he admitted in his private correspondence, it is impossible to think of mind and matter both as being distinct substances and also as being, in some sense, united. The fact of mind being united with matter in a person – our experience of ourselves as embodied minds – cannot be accounted for on Cartesian principles. This book rejects the panaceas of the Double Aspect Theory and the Identity Theory and investigates the possibility of accommodating this experience within a conceptual framework derived from Kant, the basis of which is the concept of mind, not as immaterial substance, but as a subject related, in experience, to its objects.