The High Priestess is the creator of ideas. Ideas are formed in the feminine energy and manifest in the masculine.
For further research into the relationship between Shiva and Shakti I recommend the link mentioned in my blog on feminine energy.
The High Priestess is intuition, understanding and inner wisdom. She is influenced by the Moon, the planet ruling the emotions and she holds inner secrets.
In the Rider Waite deck, the High Priestess is depicted wearing a crown of the new moon, the full moon and the and waning moon - the stages of womanhood - the maiden, the mother and the crone.
This crown is also the head of Hathor, the Egyptian goddess of love, joy music and womanhood and "Lady of the Stars" The High Priestess is also a represantaion of Persephone, the Greek goddess of Spring and new birth.
Her scroll shows the Tora which is Divine Law according to the Kabbala. It is a symbol of higher wisdom. The pillars flanking her throne are Boaz (severity) and Jachim (mercy) as mentioned in the the temple of Solomon. These pillars in black and white, again show the duality of the being.
The pomegranate is the symbol forPersephone, femininity and fertility - fertility of ideas and creation.
The High Priestess is saying "What does my inner voice tell me about my situation?", "What does my soul need?" "Am I pursuing something that I feel I should need rather than what I truly and passionately need?"