The almighty Shiva manifested in the form of Sthanu (Pillar) from his imperceptible form and looked at Lord Brahma. Lord Brahma then commenced his creation and established the norms of Varna ashrama. He also created ‘Soma’ which is required for the performance of ‘Yagya’. This world, including all the deities are the embodiments of Soma. The deities eulogize Lord Shiva by chanting the mantras of ‘Rudrashtadhyay’.
Once, Lord Shiva was sitting surrounded by all the deities. On being requested by the deities to shed light on his mysterious self, Lord Shiva said—
“I was present before the beginning of time and I will be present forever. Everything originate from me and get submerged in me ultimately. I am the Lord of Brahma. I am the truth itself. I manifest myself in the forms of Rigveda, Samaveda, Yajurveda and Atharvaveda. I am the light as well as the darkness. I am Brahma, Vishnu and Mahesh. One who is aware of my omnipresence is the only person who is worthy of being called an enlightened one.”
This way, after enlightening the deities on his myssterious self Lord Shiva disappeared.