The ancient Israelites envisaged the universe as a flat disc-shaped Earth floating on water, heaven above, underworld below.[6] Humans inhabited Earth during life and the underworld after death; there was no way that mortals could enter heaven, and the underworld was morally neutral;[7][8] only in Hellenistic times (after c. 330 BCE) did Jews begin to adopt the Greek idea that it would be a place of punishment for misdeeds, and that the righteous would enjoy an afterlife in heaven.[8] In this period too the older three-level cosmology in large measure gave way to the Greek concept of a spherical earth suspended in space at the center of a number of concentric heavens.[9]