the revelations of the teaching as they took place through the various kalpas, and in Laozi’s transmission of the Daode jing to Yin Xi, and as manifested in the Three Caverns and their various subdivisions.
This passage identifies the Three Caverns as the culminating organizational expression of Daoist revelation history, placing them within a cosmological-temporal framework of kalpic transmission.
, Daoism Handbook, 2000thesis