This book tries to unravel the diverse currents of thought that converge in the underground movement. Three main tributaries are considered: the individualistic, romantic, anarchist and amoral philosophies that culminate in Hesse; Oriental philosophies that, beyond collars and poses, have seriously influenced the underground by giving it an alternative vision to the world, based on flux and transformation rather than Greek immutability and Judeo-Christian dualities; and, finally, psychedelic philosophies, born of experiments with substances that change the brain connections and confirm the existence of different states of consciousness, posing a relativism of reality against the positivist dogma of immaculate perception. In fact, all these philosophies are irrational, question the monopoly of rationalism as the only method of knowledge and reflect the underground struggle against reason turned into a gendarme at the service of the ruling classes; domination much more perverse and subtle than the physical, which does not need police or prisons, because it is inside the brain itself.