Hearing is the function assigned to the Hierophant. The Hebrew letter Vau means nail, and is also the conjunction "and." The ornament, hanging from the crown of the Hierophant and passing behind his ears, is a conventionalized yoke. A yoke is something that joins together, again symbolizing union.
The Hindu word for union is Yoga. This card symbolizes Interior Hearing, or the development of intuition by certain practices of Yoga.
This that we call interior hearing is the real inner teaching, coming from your own Inner Self, your true Teacher. That Self is represented by the Hierophant. In this connection we must caution you that the true interior hearing is not the negative, lower psychic types of clairaudience. The difference is readily distinguished by the quality of what is heard. Intuition is above reason, but never contrary to it, and it never urges you to do an unethical or selfish thing.
The pillars represent the Law of Polarity, or the interplay of the pairs of opposites. Their capitals show a ball and socket pattern and an acorn surrounded by oak leaves. This symbolizes the union of opposites.
The design of the wards of the crossed keys is a bell. This symbolizes sound vibration used in hearing, and is also a hint that sound has a practical value in unlocking the gates of your Inner Temple. The two ministers who kneel before the Hierophant represent desire and knowledge, as indicated by the roses and lilies on their garments.