The High Priestess card is for me one of the most interesting cards of the major Arcana. Here we have a powerful woman, on her head is the triple moon crown or the crown of Isis the great Egyptian mother goddess , Queen of Magic – and her crown represents the three visible phases of the moon and of the mother maiden and crone phases of life.
On her left and right are one black and one white pillar the black one is marked B and the white one marked with J.  These initials stand for Boas and Jakim. Which correspond to Yin and Yang, representing the dark and the light, above and below..
The crescent moon at the base of the card represents the astrological sign of Taurus, which is a grounded sign – and of the night, your subconscious and also your own spirituality and intuition.