Self-Luminous Splendor
Tejas ('radiance,' 'brilliance,' 'effulgence') is the Lord's self-luminous quality — the divine light by which He is visible to Himself without requiring any external illumination, and by which He illuminates all other beings. The Upaniṣads declare: tameva bhāntam anubhāti sarvam tasya bhāsā sarvam idam vibhāti — 'By His light alone does everything else shine; by His radiance, all this world is lit.'
Self-Illumination and Other-Illumination
Brahman is svayaṃjyoti (self-luminous) — He knows Himself without any external knower; He requires no other consciousness to be conscious of. This is unlike the jīva, which requires the Lord's consciousness flowing through its dharma-bhūta-jñāna to know anything. The tejas of Brahman is the original light; the jīva's knowledge is a reflection or participation in that light.
Tejas in Archa Form
In the temple, the Lord's tejas is revealed in His divine form (divyamaṅgalavigraha) — the golden glow of the deity, the brilliance of the gemstones used in decoration, the pure white light of camphor flames during ārtī — all of these are understood as symbolic participations in the Lord's tejas. Āzhvārs frequently describe being overwhelmed by the Lord's radiance.
Vaikuṇṭha's Light
In Vaikuṇṭha, there is no sun, moon, or fire — the Lord's own tejas illuminates the entire realm (na tatra sūryo bhāti na candratārakaṃ...). This scriptural statement affirms that tejas is not merely a metaphor for glory but a real quality of Brahman's being.