Einstein left me for a while to the tumult of ideas that he had roused up in me. After I had overcome the first shock, I sought to gain a haven in the idea that arose out of the first shadow-argument, in which the spherical bodies occurred that seek to escape towards infinity on the right but reappear, instead, at enormous distances on the left. Has anyone ever had presentiments of this kind of world? Perhaps something of the sort is to be found in earlier books of science? If so, they have escaped my notice. Yet, a passage of a poet occurs to me. It is to be found in a volume by Heinrich von Kleist; it is a volume dealing only with earthly matter and bare of astronomical ideas. Imagine a book the subject of which is a puppet-show, containing, in the middle of it, a section foreshadowing Einstein's universe! Quite by chance Kleist comes to speak of "the intersection of two lines which, after passing through infinity, suddenly appear on the other side, like a picture in a concave mirror, which moves away to infinity and suddenly returns again and is quite close," and, quite in accordance with our new cosmology, he declares: "Paradise is locked and barred, and the cherub is behind us; we must make a voyage round the world, and see whether we cannot discover an exit elsewhere at the other end perhaps." Perhaps poets of the future will busy themselves with this universe; not lyrical poets, but descendants of Hesiod, Lucretius, or Rückert. They will express in verse that Einstein's world offers a source of consolation to tormented spirits which have sickened of Kant's antinomies. For in this still almost immeasurable world the fateful conception "infinite" has been made bearable for the first time. In a certain way it relieves us from what is quite inconceivable, yet into which we are usually driven, and forms a bridge between the thesis "finite" and the antithesis infinite. We are brought to a common stream, in which both conceptions peacefully flow together. There was no mention of this in our talk, and I had good reason for being cautious about following out the theme along these lines. I must not allow any doubts to arise on this point: Einstein, himself, clings with unerring logic to the strict mathematically defined conception of infinity, and allows no compromise with the non-infinite. When I, on some previous occasion, sought to lead him on to a compromise, involving a transition-boundary, it availed me nothing that I quoted Helmholtz to support the possibility of such an operation: my effort came to an abrupt end. * * * * * * * *