(O Astrid, I might expect an interpretation like that from a Thoth fan, though it figures in my interpretation as well, and I’m not a Book of Thoth fan, though Hermes Trismegistus ALIAS Thoth has my rapt attention.)
Fulgour, if I might suggest a solution to your bepuzzlement (or lack thereof): in bardic numeration O-ayin is four, so there are TWO of them that have been multiplied to produce XVI and two, of course, falling from the tower itself (two little ‘emperor-ayins’).
M. le kwaw, intriguing stuff. Bardic XVI is S-shin, the letter assigned to fire in Sefer Yetzirah. It is the ‘mother letter’ replacing the U or O of the Logos (AUM) and thus for the Gnostic is the thinker or Holy Spirit, whose seat (in the archetypal world or Monad) is sagittary. This is the sign preceding, and thus leading to, the sign straight back (from cancer-the-breasts or straight out), the direction of self (the tenth, the Shekhinah): XVI is the thinking (Sophia or Holy Spirit) that leads to self-knowledge (God the Father, or knower).
As the central fire of the Throne world, shin crowns the middle pillar (the year, one aspect of sol or gold) of the seven pillars-of-wisdom in the alchemical vessel (rounds 9-8-7-6-5-4-3, or silver, mercury, copper, axis mundi, iron, tin, lead), which, as copper’s (Venus’s) proper ‘mate’ corresponds to Hephaestus or Vulcan, who rules no sign because his column has no width, being the vertical diameter. I have of late taken this to indicate an ancient understanding that the year was earth’s central fire journeying about the sun or outer ‘fire’ (actually air’s receptivity to fire), the sun's or outer fire’s own journey being the great year (‘precession’), which entails the entire physical heavens’ revolution about the signs of the zodiac (meaning man). The planets ‘cluster about’ Vulcan in the sense that he is the middle pillar, the central fire, but only earth’s crust’s rotation, luna’s orbit, and the heavens themselves (roughly every 25,000 years) revolve about earth (meaning us), since the planets without revolve about the sun without (yet there is an inner sun, hidden to us... but I'll shut up now)