The conception of Ardhanarishvara may have been inspired by Vedic literature's composite figure of Yama-Yami, the Vedic descriptions of the primordial Creator Vishvarupa or Prajapati and the fire-god Agni as "bull who is also a cow," the Brihadaranyaka Upanishad's Atman ("soul") in the form of the androgynous cosmic man Purusha and the androgynous myths of the Greek Hermaphroditus and Phrygian Agdistis. The Brihadaranyaka Upanishad says that Purusha splits himself into two parts, male and female, and the two halves copulate, producing all life – a theme concurrent in Ardhanarishvara's tales. The Shvetashvatara Upanishad sows the seed of the Puranic Ardhanarishvara. It declares Rudra – the antecedent of the Puranic Shiva – the maker of all and the root of Purusha (the male principle) and Prakriti (the female principle), adhering to Samkhya philosophy. It hints at his androgynous nature, describing him both as male and female.