The gods in the Rig-Veda are mostly personified concepts, who fall into two categories: the devas – who were gods of nature – such as the weather deity Indra (who is also the King of the gods), Agni ("fire"), Usha ("dawn"), Surya ("sun") and Apas ("waters") on the one hand, and on the other hand the asuras – gods of moral concepts – such as Mitra ("contract"), Aryaman (guardian of guest, friendship and marriage), Bhaga ("share") or Varuna, the supreme Asura (or Aditya). While Rigvedic "deva" is variously applied to most gods, including many of the Asuras, the Devas are characterised as Younger Gods while Asuras are the Older Gods (pūrve devāḥ). In later Vedic texts, the Asuras become demons.