Hexagram 24, Returning, is made up of the trigrams for thunder within the earth:
Hexagram 25, Without Entanglement, has thunder below earth’s complement, heaven:
Thunder is the vital spark, often human will and initiative. In a time of Returning, the wise old kings would ‘close the gates. Itinerant merchants did not travel, and the prince did not inspect the regions.’
I think the kings are showing earth wisdom here: mothering the impulse of thunder, holding it back from expending its energy prematurely. By withholding it from ‘business as usual’, it nurtures the energy; it keeps it growing in the depths rather than being dispersed on the surface.
This is also a way to understand what happens in the Judgement, the oldest idea of Returning. Someone can walk away from the bustle of the town, and ‘go out and come in without anxiety’ according to the natural direction of their own path. They are fostering their inner sense of direction by separating it out from their society’s demands.
And so being Without Entanglement follows. When that inner spark of personal initiative has become independent of the pressures of social expectations, when it’s been kept well away from routine busy-ness for a time, then it’s liberated for a far freer, more complete connection with heaven.
Hexagram 25’s thunder can be the energy released when you’re not investing yourself in things that are not really within your control. And more than that, it enters into a real connection that may have been in danger of disappearing among the entanglements. The thunder turns out to have a natural affinity with heaven.
I wonder if the entanglements could be related to the concept of maya, illusion? They can certainly be an artifical world of demands and agendas, self-created or passed on from society. Hexagram 24 loosens their grip and stores up energy for Return; Hexagram 25 is the re-alignment that naturally follows from this time of retreat.
Incidentally, the thunder is almost always stored safely on the inside in the Upper Canon (hexagrams 1 through 30). Only at Hexagram 16, Enthusiasm, does it come out to play and create big images. This pattern is almost perfectly reversed in the Lower Canon (hexagrams 31 to 64): the thunder is out in the world, except in hexagram 42, when it’s on the inside, and of course in Hexagram 51, where it’s doubled.