Tarot Empress wears the Egyptian hieroglyph of Hathor, meaning House of Horus on her throat. This hieroglyph depicts a wall with a door. A door is a soft part of a wall which is an apt depiction of this card. Daleth, the Hebrew letter which corresponds to this card, means door.
Be aware that the Hindu Goddess Kali is a door. More info on Kali.
Tarot of the Morning Star Deck available from Magus Books