​The phrase "Take thou the Sun and the Moon, and let them be made into one, and it will be a thing that shall not fail thee" is an alchemical instruction found in the Mutus Liber ("Silent Book"). This 17th-century text consists solely of symbolic illustrations depicting stages of the alchemical process, with no accompanying text. The phrase refers to the alchemical concept of combining the sun (symbolizing gold) and the moon (symbolizing silver) to achieve the philosopher's stone, a legendary substance believed to grant immortality and the ability to transmute base metals into gold. This combination represents the union of opposites, a central theme in alchemical tradition.