The teaching that travelled
The cosmology, in the most condensed form The White Book offers: there is one consciousness, expressing through every form. The individual self is that consciousness experiencing itself in particular constraint. The work of a life is to remember the consciousness behind the form, to lift the assemblage point (in Castaneda's language) or the chakra (in Vasudev Baba's) — to know, from inside the experience, that you are God expressing.
The three-step arc of chapters 18 / 19 / 20 — The Closed Mind → Opening the Mind → The Virtue of Experience — is the operational instruction. It is also the same arc Steiner reached from inside Geisteswissenschaft, and the same shift Levin describes in TAME as moving an agent into a larger cognitive light cone. Different vessels, converging teaching.