Similarly, if time is curved, the idea of the cyclic return of time naturally (though not inevitably) follows, and the division of the greater cycles into lesser loops; for it is easier to assign this elliptical movement to time than any other, by reason of the orbital movements of the planets and their satellites. What results from conceptions of this order? Amazing things! If our space is curved in higher space, you may be looking toward the back of your own head. If time flows in cycles, in travelling toward to-morrow you may be facing yesterday.
This "eternal return," so far from being a new idea, is so old that it has been forgotten. Its reappearance in novel guise, along with so many other recrudescences, itself beautifully illustrates time curvature in consciousness. Yugas, time cycles, are an integral and inexpugnable part of Oriental metaphysics. "Since the soul perpetually runs," says Zoroaster, "in a certain space of time it passes through all things, which circulation being accomplished, it is compelled to run back again through all things, and unfold the same web of generation in the world." Time curvature is implicit in the Greek idea of the iron, bronze, silver, and golden ages, succeeding each other in the same order: the winter, seed-time, summer and harvest of the larger year. Astrology, seership, prophecy, become plausible on the higher-time hypothesis. From this point of view history becomes less puzzling and paradoxical. What were the Middle Ages but a forgetting of Greek and Roman civilization, and what was the Renaissance but a remembering of them—a striving to re-create the ruined stage-settings and to re-enact the urbane play of Pagan life. The spirit of the Crusades is now again animate throughout Europe. Nations are uniting in a Holy War against the Infidel de nos jours.
But it is in the individual consciousness that time curvature receives its most striking confirmation—those lesser returns and rhythms to which we give the name of periodicity. Before considering these, however, a fundamental fallacy of the modern mind must be exposed.