John Horgan is a scientifically-trained writer, with the unemphatic skepticism that usually goes along with that. He expects things to be plausable even when they are not amenable to controlled testing. From the way he even-handedly discusses religions and their gods, as well as the very idea of God, I would make him an agnostic. "Can mystical spirituality be reconciled with science and, more broadly, with reason?" he asks, in his introduction. He is a journalist, and so his seeking takes the form of interviews with people prominent in various of the areas -- the "perennial philosophy", psychedelic drugs, meditation, and so on -- that are associated with the rather imprecise term "mysticism". In preparation he studies with some care the writings and reputations of those he will talk to as well as the "classical" works on mysticism and altered mental states. Moreover, he brings with him the memory of an extreme psychedelic episode of his own.
Then, basically, he subjects the claims, wild and mild, of the seekers, sages, and scholars with whom he talks to the test of a skeptical rationality. Sometimes they fail on Horgan's terms; sometimes they even fail on their own terms. But fail they do. To his credit it never seems a foregone conclusion that he will not embrace one or another approach. He is, after all, himself a seeker -- though of course also an author with an eye to the market -- but one for whom the need for the consolations or exhaltations of an altered perception seems to be qualified by his firm grounding in this world.
This book is easy to read and entertaining. The writing is clear and accomplished without being grandiose, and Horgan seems a civilized and warm-hearted guy. But he is not really into psychedelics or other drugs (although he did participate in an ahuasca ceremony for research purposes), and in the end he rather mildly concludes that perhaps the Zen exhortation to just pay attention to your life is the best we can usually do. I suspect that, for those of us that share his rational humanist outlook, our spiritual yearnings will have to be satisfied in the low-key way he finally arrives at.