An Outline of Occult Science: An Occult and Philosophy Classic By Rudolph Steiner! AAA+++

Human understanding, as it works in everyday life and in ordinary science, is actually so constituted that it cannot penetrate into superphysical worlds. This may be proven beyond the possibility of denial. But this proof can have no more value for a certain kind of soul-life than the proof one would use in showing that man's natural eye cannot, with its visual faculty, penetrate to the smallest cells of a living being, or to the constitution of far-off celestial bodies.