The asuras are defined by who they are not. They are a-suras meaning not gods. They are the enemies of suras (gods). This was not always so, however. In the early parts of Rigveda, the most prominent deities like Varuna and Mitra are called asuras. Varuna is called ‘wise asura and king’ and ‘the all-knowing asura who established the heavens and fixed the limits of the earth’.
In these early hymns, asura denotes a divine being without any negative connotation. In the later parts of the Vedas, like the Brahmanas and Upanishads, it is mentioned that ‘the devas gave up falsehood and adopted truth, while the asuras gave up truth and adopted falsehood’.
In these later books, asuras are portrayed as the enemies of the devas (gods). Interestingly, the Persians held exactly the opposite views. In the Persian language, an ‘h’ is used in place of the Sanskrit ‘s’, so asura becomes ahura, which means god in Persian.
In fact, their chief god is called Ahura-Mazda. On the other hand, daeva means demon in Persian. This has given rise to a theory that perhaps there was a conflict between Indo-Aryans and Persians, which resulted in their opposite views towards asuras and devas.
A major milestone in the deva-asura rivalry was the Indra-Vritra battle. Vritra was the head of asuras. He kept the waters of the world captive, resulting in a huge drought. The devas led by Indra fought him, but were defeated. Indra got a special weapon called Vajra made of the bones of Rishi Dadhichi, who gave up his life for this cause. Armed with this supreme weapon, Indra was able to kill Vritra after
a 360-day battle.
Interestingly, the Rigveda talks about devav asura (asuras who have become devas), and contrasts it with asura adevah (asuras who have not become devas). Devas and asuras were born of a single father Prajapati, but developed differently due to the different choices made in their lives. Their orientation was not decided by birth, but by whether their intent and actions were noble or evil. Some asuras went on to become devas, while others remained asuras.
The Upanishads present yet another view of the two. They say that the asuras and devas go to Prajapati to understand what is soul, and how to realise their true selves. Prajapati first gives a simplistic answer which the asuras accept without much thought. After the asuras have left, the devas led by Indra question Prajapati further because they are not satisfied with the first answer. This story symbolises that understanding our true selves is a continuous learning process and only through this constant struggle, we can overcome our asura nature and bring out our deva qualities.