They’re often mentioned in the same breath as new-agey trends like crystal healing (a practice with lots of wellness cool cred but little scientific proof), but essential oils are actually backed by decades of research. We turned to Kurt Schnaubelt, Ph.D., a world-renowned aromatherapist and author of The Healing Intelligence of Essential Oils (also: the expert behind our Aromatherapy Collection), to help illuminate aromatherapy—a science that very much feels like magic.