The Black or New Moon represents the start of a new lunar cycle, and as such renewal and rebirth. Unlike the waxing crescent, which represents the rebirth of the body, the Black Moon symbolizes the renewal and rebirth of the soul before it reenters the earthly plane. The Black Moon is the eternal cosmic soup of existence where souls can recalibrate and realign with their true purpose. It also represents a cleared slate. A moment of stillness, silence, and reflection. It is the unformed thought, the gut feeling, the playful idea that catches your attention. The start of something that does not yet have a name.
The Black Moon also represents the descent into the underworld, facing a trial, and confronting personal shadows. It represents a crucial step in the hero's journey, entering into the unknown, mysterious, and potentially dangerous place to overcome its challenges and be transformed. During the Black Moon, because the Moon is not visible, the sky appears darker which makes it easier to see other celestial objects. This magically corresponds to spells about revealing what is normally difficult to see, obscured, or hidden. The Black Moon illuminates that which is normally hidden lurking in the dark, our animal or base instincts.
Exploring the dark aspects of the psyche is called shadow work. The idea of a "shadow self" dates back to the time of the Ancient Egyptians, who believed that there were 9 parts that make up a human being, one of which is the "swt", or the shadow. Sometimes independent and sometimes an aspect of the “ba”, the soul, the Shadow survives human death and travels with the “ba” to the afterlife, each night returning to the body of the deceased together.
For the ancient Sumerians, the Black Moon was a sacred but worrisome time. The disappearance of the moon in the sky was known as the "day of distress", and the King would perform special rituals to pacify the gods.