The concept of Purusha is similar to the concept of Brahman described in the later texts. As for the creation of the primordial beings (such as the gods who performed the sacrifice of the Purusha), the Nasadiya Sukta states:  Rigveda (10.121) also mentions the Hiranyagarbha (literally, golden embryo/womb/egg) that existed before the creation. This metaphor has been interpreted differently by the various later texts. The Samkhya texts state that Purusha and the Prakriti made the embryo, from which the world emerged. In another tradition, the creator god Brahma emerged from the egg and created the world, while in yet another tradition the Brahma himself is the Hiranyagarbha. The nature of the Purusha, the creation of the gods and other details of the embryo creation myth have been described variously by the later Hindu texts. The early hymns of Rigveda also mention Tvastar as the first born creator of the human world. Recounting the creation of gods, the Rig Veda does seem to affirm ‘’creatio ex nihilo’’. Rig Veda 10.72 states:  The Shatapatha Brahmana mentions a story of creation, in which the Prajapati performs tapas to reproduce himself. He releases the waters and enters them in the form of an egg that evolves into the cosmos. The Prajapati emerged from the golden egg, and created the earth, the middle regions and the sky. With further tapas, he created the devas. He also created the asuras, and the darkness came into the being. It also contains a story similar to the other great flood stories. After the great flood, Manu the only surviving human, offers a sacrifice from which Ida is born. From her, the existing human race comes into the being. The Aitareya Upanishad (3.4.1) mentions that only the "Atman" (the Self) existed in the beginning. The Self created the heaven ("Ambhas"), the sky ("Marikis"), the earth ("Mara") and the underworld ("Ap"). He then formed the Purusha from the water. He also created the speech, the fire, the prana (breath of life), the air and the various senses, the directions, the trees, the mind, the moon and other things. The Brihadaranyaka Upanishad (1.4) mentions that in the beginning, only the Atman existed as the Purusha.