Zurvanism was an ancient variant of Zoroastrianism. According to Zurvanism, the great powers of good and evil, Ahura Mazda and Angra Mainyu, were the sons of a greater god Zurvan, associated with time. According to Eudemus of Rhodes, some Persian thinkers, presumably Zurvanists, took there to be three great principles underlying the world: light, darkness, and greatest of all time (or perhaps, according to Eudemus, space). This paper explores what metaphysics might underlie these doctrines, and what contemporary options we have (...) for making sense of a metaphysics where time is the ultimate principle. Among the options explored is the option that despite appearance many of the entities of the concrete world are identical to stretches of time, or are somehow aspects of stretches of time; that they include times as parts, or are included in times as parts; that they are somehow properties of time; or hylomorphic compounds of which time is the matter; that the world is somehow a mixture of time, light, and dark; or that somehow the ends or teloi of everyday objects and processes are to be found among good, evil, and time. (shrink)