Published here for the first time in English, these six public lectures are among Rudolf Steiner's most inspired-and inspiring-explorations of anthroposophy as a true science of the spirit. Our age provides abundant explanations of the universe, its nature and evolution. But underlying most scientific modalities is a passive engagement with self and world, a taking-for-granted of the faculty of thinking, and, as a result, an indifferent arranging of phenomena through logical inference. But the question remains: What is thinking? A product of chemical processes in the brain, or a spiritual activity through which we become participants in a spiritual cosmos? This is Rudolf Steiner's starting-point in all his work. He aims to cast off the unnecessary limits imposed on knowledge by a science that fails to examine its most fundamental epistemological premises. The lectures here are a remarkable contribution to this life-long project-a compelling, cloquent, insightful study and affirmation of our very humanness. Speaking to a youthful academic audience, Steiner does not confine himself to the arbitrary delineations of codified academic disciplines; on the contrary, he breaks down barriers, builds bridges, envisions a future academy in which the paths of knowledge are broadened through a genuine science of initiation to encompass our role as members and, ultimately, co-creators of the physical-soul-spiritual universe.