the Yajurveda. 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, "Asura" comes to mean demon. The Rigveda has 10 Mandalas ('books'). There is significant variation in the language and style between the family books (RV books 2–7), book 8, the "Soma Mandala" (RV 9), and the more recent books 1 and 10. The older books share many aspects of common Indo-Iranian religion, and is an important source for the reconstruction of earlier common Indo-European traditions. Especially RV 8 has striking similarity to the Avesta, containing allusions to Afghan Flora and Fauna, e.g. to camels ( = Avestan uštra). Many of the central religious terms in Vedic Sanskrit have cognates in the religious vocabulary of other Indo-European languages (deva: Latin deus; hotar: Germanic god; asura: Germanic ansuz; yajna: Greek hagios; brahman: Norse Bragi or perhaps Latin flamen etc.). In the Avesta, Asura (Ahura) is considered good and Devas (Daevas) are considered evil entities, quite the opposite of the Rig Veda. Cosmic order Ethics in the Vedas are based on the concepts of Satya and Ṛta. Satya is the principle of integration rooted in the Absolute. Ṛta is the expression of Satya, which regulates and coordinates the operation of the universe and everything within it. Conformity with Ṛta would enable progress whereas its violation would lead to punishment. Panikkar remarks: The term "dharma" was already used in Brahmanical thought, where it was conceived as an aspect of Rta. The term rta is also known from the Proto-Indo-Iranian religion, the religion of the Indo-Iranian peoples prior to the earliest Vedic (Indo-Aryan) and Zoroastrian (Iranian) scriptures. Asha (aša) is the Avestan language term corresponding to Vedic language ṛta. Upanishads The 9th and 8th centuries BCE witnessed the composition of the earliest Upanishads. Upanishads form the theoretical