The divine spatial abstraction Caelum is a synonym for Olympus as a metaphorical heavenly abode of the divine, both identified with and distinguished from the mountain in ancient Greece named as the home of the gods. Varro says that the Greeks call Caelum (or Caelus) Olympus. As a representation of space, Caelum is one of the components of the mundus, the world or cosmos, along with terra (earth), mare (sea), and aer (air). In his work on the cosmological systems of antiquity, the Dutch Renaissance humanist Gerardus Vossius deals extensively with Caelus and his duality as both a god and a place that the other gods inhabit.