The notion of the rhythmical recurrence of cosmic
events may well have
developed out of the charac-
teristics
of the solar year, the periodicity of the lunar
phases, the round of the
seasons in regular order, the
life cycle of the individual human being.
That the idea
of birth, maturation, senility, and death followed by
rebirth interested the ancients is shown by the many
myths and rites in
which this series of events is figured.
We no longer possess the documents
which might have
provided the evidence on which the concept was based,
assuming that such documents ever existed, but there
are certain hints from
early intellectual history which
suggest an answer. The observation of
astronomical
rhythms goes back to Babylonian times; the Pythagor-
eans as early as the sixth century
B.C. had speculated
on numerical repetitions such as are found in decimal
fractions; in India various theories about ages, pe-
riods, recurrences were elaborated; and the early
Greek
philosophers in general were given to mentioning
cyclical
changes in the transmutations of the four ele-
ments: earth, water, air, and fire. In many of the think-
ers who believed in cosmic cycles one also finds
traces
or definite assertions of the transmigration of souls.
