Which are those features? This book proposes a twofold answer. It draws attention to the layered nature of human consciousness, in which different manners of experience are superimposed on each other. This goes a long way toward accounting for the universal religious belief in some kind of transcendental world, a "higher" reality, different from "ordinary" reality. The layering of consciousness comes about in childhood and gains in prominence with the acquisition of a first language, which is the second feature highlighted in this book. Together, these features explain a variety of "normal" religious behaviours and beliefs, and account for the possibility of mystical experience. They also explain the occurrence of behaviours that do not augment evolutionary fitness.