The traditional astrological glyph for the moon, and one of the alchemical symbols for silver.
In the Hermetic sciences, the moon represented the feminine, liquid, passive principle- alchemical Mercury. The hieros gamos, or divine marriage, is the combining of the solar and lunar principals to form the divine androgyne- the highest form of spiritual attainment.
The metal silver is second in value only to gold. From Roman times onward, silver was purported to repel or even kill demons. This belief carried into the Middle Ages, where it was believed demons, witches, and other evil creatures could be killed with silver bolts or bullets. This is also the origination of the vampire trope whereby the creatures cannot be reflected in mirrors- being a pure metal, silver objects and silver-backed mirrors could not reflect impurity.
|A Wiccan moon-symbol of blessing|
|High Priestess of the tarot, with lunar emblem representing the unconscious|