[This paper, delivered at the Colloquium on Symbolism in Paris in June 1964, appeared in the Cahiers internationaux de symbolisme 6, Brussels 1964, pp. 3-26. The version printed here has been condensed (with the permission of the author) by omitting paragraphs of a technical nature on pages 5 and 8 of the original, as well as an account (pp. 17-23) of the topography of the Eighth Clime. The com...