text: The practice of alchemy in the Western world, based on a Hellenistic and Babylonian approach to planetary astronomy, often ascribed a symbolic association between the seven then-known celestial bodies and the metals known to the Greeks and Babylonians during antiquity. Additionally, some alchemists and astrologers believed there was an association, sometimes called a rulership, between days of the week, the alchemical metals, and the planets that were said to hold "dominion" over them. There was some early variation, but the most common associations since antiquity are the following: