States of profound meditative concentration, the jhānas are central to the earliest Buddhist teachings. For centuries in Southeast Asia, oral yogāvacara (yoga practitioner) lineages kept traditional jhāna practices alive, but in the nineteenth and twentieth centuries, reforms in Theravāda Buddhism downplayed the importance of jhāna in favor of vipassanā (insight) meditation. Some began to consider the jhānas to be strictly the domain of monastics, unattainable in the context of modern lay life. In recent years, however, there has been a resurgence of interest in the jhānas, and as researcher Paul Dennison shows, the esoteric and sometimes "magical" pre-reform practices of Southeast Asia hold powerful potential for modern lay practitioners living in a more scientifically minded world. Drawing on traditional Buddhist doctrine, teachings from lesser-known meditation texts such as the Yogāvacara's Manual, and findings from the first in-depth, peer-reviewed neuroscience study of jhāna meditation, Dennison unpacks this ancient practice in all its nuance while posing novel questions about perception, subjectivity, and the nature of enlightenment.