JES BERTELSEN (b. 1946) is a Danish spiritual teacher and author. He is the leader of the Vækstcenter (Growth Center) in Nørre Snede in Denmark. He has a PhD in the History of Ideas from Aarhus University, Denmark, where he also taught for more than a decade. He has written 20 books in Danish ranging from a thesis on Kierkegaard, through books on self-development and depth psychology, to the advanced meditation texts of later years. His teaching and his later books are based on a systematic experiential investigation of the nature of consciousness, using comparative analyses of Eastern and Western consciousness practices, as well as modern psychological, philosophical, and scientific approaches.His latest offerings are (2008) Bevidsthedens flydende lys: Betragtninger over begrebet apperception hos Immanuel Kant og Longchenpa (The Flowing Light of Consciousness: Reflections on the Concept of Apperception in Immanuel Kant and Longchenpa) and (2009) a research article published in the science magazine NeuroReport, “Long-term meditation is associated with increased gray matter density in the brain stem” (coauthored with Peter Vestergaard-Poulsen, Martijn van Beek, Joshua Skewes, Carsten R. Bjarkam, Michael Stubberup, and Andreas Roepstorf).