What does Winter dream of?
In observational astronomy, there's a phenomenon called an "epicycle," a cycle within a cycle.
If you watch a particular planet from night to night—Venus, say—you'll see her move along her regular path. Then she stops and goes backwards. She makes a widdershins loop in the sky, then resumes her regular course.
Of course it's all a matter of perspective and bodies in simultaneous motion. But what it looks like is time in reverse.
The Year is Earth's story. From youth she waxes into ripe maturity and wanes away into age.
And now the serpent catches its tail in its mouth, time runs backwards, and old woman becomes young girl.