“As above, so below” has many interpretations, the simplest of which is that whatever happens on earth is reflected in the astral plane. Another interpretation is that the microcosm, such as the world of the individual, is affected by the macrocosm, such as society at large. In essence, the expression looks at any place there is a duality, one where half of the duality is deemed “above” while the other half is deemed “below,” and tries to establish a relation between the two.
