A name given to the universe in Purāṇic cosmogony because Brahmā (equated here with Puruṣa) is said to be born from the eternal, unmanifest first cause inside a golden egg. (This is perhaps connected with the idea that brahmins, like birds, are dvija, ‘twice-born’.) According to Manusmṛti (1.12), after a year, Brahmā divides the egg (himself) in two through the power of thought, and thus creates the physical and psycho-physical worlds. The egg, however, remains unhatched, and so in the Purāṇas the universe is conceived as a closed, egg- or ball-shaped entity. It is divided into twenty-one zones, comprised (from top to bottom) of six heavens, the earth, the seven lower regions of Pātāla (inhabited by various mythical creatures, such as nāgas), and seven hellish regions (naraka).