This explanation from Waite shows how, while still in the GD, he saw the High Priestess as Shekinah and as Gimel and the astrological Moon on the GD Tree:
"The Shekinah in transcendence, keeping the Path of Gimel – religion in attainment. She is Divine Law wherein is the path of attainment. She is the Moon . . . the Queen of Heaven. Her light comes from the Eternal (Kether). She is the Guardian of the Gate of Daath. She is Virgin, Bride, Mother [triple crown], because she is the splendour of purity in all her states and planes. She is Anima Mundi. For us, however and for our concerns, she is the restorer of worlds. It is for this reason that she is the Gate of Yetzirah, or the Guardian who stands thereat. Waite, “The Tarot and the Rosy Cross”
"The Tarot and the Rosy Cross" is the third paper in this pdf:
https://tarotcirkel.files.wordpress.com/2014/05/artikels-tarot-waite.pdf
There's much, much more about the High Priestess in this paper.
For Waite, she was, above all, the Shekinah, “the prevailing genius of the esoteric, withdrawn power” (PKT). In The Holy Kabbalah, he speaks of her as she “who sits between the Pillars of the Eternal Temple with the Book of the Secret Law lying open on her sacred knees."
The Book of the Secret Law = the TORA scroll and the Secret Doctrine itself.