As above, so below. As within, so without.

Many ask how astrology works. Here is the best explanation I know of: “True without error, certain and most true: that which is above is as that which is below, and that which is below is as that which is above, for performing the miracles of the One Thing; and as all things were from One, by the mediation of One, so all things arose from this One Thing...”  

~The Emerald Tablets of Hermes