The feeling that we call “I” is an illusion. There is no discrete self or ego living like a Minotaur in the labyrinth of the brain. And the feeling that there is—the sense of being perched somewhere behind your eyes, looking out at a world that is separate from yourself—can be altered or entirely extinguished. Although such experiences of “self-transcendence” are generally thought about in religious terms, there is nothing, in principle, irrational about them. From both scientific and a philosophical point of view, they represent a clearer understanding of the way things are. Deepening that understanding, and repeatedly cutting through the illusion of the self, is what is meant by “spirituality” in the context of this book.