In Hinduism, the Asura (Sanskrit: असुर) are a group of power-seeking deities, sometimes considered sinful and materialistic. They were opposed to the Devas. Both groups are children of Kasyapa. However, in early Vedic religion Asuras and Devas both were deities who constantly compete with each other, some bearing both designations at the same time. Asura is cognate to Ahura?indeed, the Oxford English Dictionary recognizes the use of the term in reference to Zoroastrianism, where “Ahura” would perhaps be more appropriate?and Old Norse “?sir”, which implies a common Proto-Indo-European origin for the Asura and the ?sir. In entry 48 of his Indogermanisches etymologisches W?rterbuch, Julius Pokorny reconstructs this common origin as *ansu-.
Mahishasura Statue, Chamundi hills, near Mysore.
The negative character of the Asura in post-Rigvedic religion evolved over time. In general, the earliest text, the Rigveda, has the Asuras presiding over moral and social phenomena (e.g. Varuna, the guardian of Ṛt?, or Aryaman, the patron of marriages) and the Devas presiding over natural phenomena (e.g. Ushas, whose name means “dawn”, or Indra, the leader of the Devas). However by the time of the Brahmana texts the Asuras have developed a negative character.
In later texts, such as the Puranas and Itihasas, we find that the “Devas” are the good beings and the “Asuras” the bad ones. According to the Bhagavad Gita (16.6), all beings in the Universe partake either of the divine qualities (Daivi Sampad) or the material qualities (Asuri Sampad). The sixteenth chapter of the Bhagavad Gita describes the divine qualities briefly and the materialistic qualities at length. In summary, the Gita (16.4) says that the Asuric qualities are pride, arrogance, conceit, anger, harshness, and ignorance.
The Padma Purana says that the devotees of Vishnu are endowed with the divine qualities (viṣṇu-bhaktaḥ smṛto daiva) whereas the Asuras are just the opposite (āsuras tad-viparyayaḥ).
As per P.L. Bhargava (in his book ?Vedic Religion and culture?), ?The word Asura including its variants asurya and aasura occurs 88 times in the Rg Veda, 71 times in the singular number, 4 times in the dual, 10 times in the plural, and 3 times as the first member of a compound. In this the feminine form asuryaa is included twice. The word asurya has been used 19 times as an abstract noun, while the abstract form asuratva occurs 24 times, 22 times in each of the 22 times of one hymn and twice in the other tow hymns.?
P.L. Bhargava believes that in the most of the ancient hymns, the word Asura is always used as an adjective meaning ‘powerful’ or ‘mighty’. Two generous kings of the Rigveda as well as some priests have been described as Asura. One hymn requests a son who is an Asura. In 9 hymns, Indra is described as Asura. 5 times he is said to possess asurya and once he is said to possess Asuratva. Agni has total of 12 Asura descriptions, Varuna has 10, Mitra 8, and Rudra 6. Bhargava gives a count of the word usage per every Vedic deity.
As per Bhargava, the word slowly took on a negative connotation towards the end of the (Rig)Vedic period. The Avesta (the book of the Zoroastrians) describes their supreme God as Ahura Mazda (compare Vedic Asura Medhira) ? Mighty and Wise. For them, the word Deva (daeuua) is negative. Asura is therefore regarded as an epithet. Ravanasura means mighty Ravana. Ravana was a Brahmana ? Rakshasa. There was no ?Asura Jati? in the way that there were Rakshasas, Daityas, Devas and Brahmanas. --Wikipedia
According to the Samkhya Karika, Asuri received the Samkhya philosophy directly from Kapila. In other words, he was second in the lineage of Samkhya gurus.