Louis Pauwels and Jacques Bergier, The Morning of the Magicians page 246

Einstein, with his sublime intelligence, was able, in a flash of illumination, to catch a glimpse of the space-time relationship, but without completely understanding or integrating it into his scheme of things. To communicate his discovery at a communicable and intelligible level, and to help him to recapture his own illuminating vision, he drew the sign λ representing the trihedral angle. This sign is not a schema of reality and means nothing to the mass of mankind. It is a signal, a rallying cry to all workers in the field of mathematical physics. And yet all the progress made in this field by the greatest intellects will only succeed in discovering what this trihedral symbol evokes, but will not be able to penetrate the Universe where the law of which this symbol is an expression actually operates. At least, at the end of this forward march, we will know that this other Universe exists.