One interpretation is that this means that the equinox has precessed through these constellations (and in fact all the others too) three times, and that the zodiacs indicate (among other things) the passage of three precessional cycles. This interpretation corresponds to the first interpretation given above. But Blavatsky gives another interpretation:
the three ‘Virgins,’ or Virgo in three different positions, meant, with both [the Hindus and the Egyptians] the record of the first three ‘divine or astronomical Dynasties,’ who taught the third root-race; and after having abandoned the Atlanteans to their doom, returned (or redescended, rather) during the third sub-race of the fifth, in order to reveal to saved humanity the mysteries of their birth-place – the sidereal Heavens.8
Thought you might enjoy this.
It was part of my search on Dendera Zodiac and ISIS/ Virgo