In Indian iconography, it is the fires of Shiva (as form of the Self) which purify the mind. Shiva’s fire is a fire of Self-knowledge. Shiva’s fire burns away our attachments and illusions regarding the empirical world and empirical self.
The Brahmanda Purana illustrates the potency of the fires of the Self. In the narrative, a group of sages go into the forest to seek out Shiva (‘The Pure One’). There they meet fierce form of Shiva, covered in ash (ch 27, verse 10-115). Shiva tells the sages of the importance of fire and ash:
I shall explain this to you….Fire, in Shaivism, is the fire of knowledge. This is called Jñãnãgni: Jñãna translates as knowledge and ãgni translates as fire. With knowledge of the supreme Self all our illusions and delusions regarding the empirical world, or object world, are burned away. The product of such fires of knowledge is ash.
I am Agni accompanied by Soma…
all the worlds have resorted to the fire made and unmade.
The whole world, mobile and immobile, is burned many times by fire…
Everything can be achieved through ash.
It is excellent and sacred. (verse 106- 107)
In Shankara’s terms, it is the knowledge of Brahman (the Self) that destroys the illusions. In a commentary on the Mundaka Upanishad, Shankara says as much:
He who knows that he himself is this Brahman (the Self) the highest and the immortal placed in the hearts of all living beings, destroys the dense tendencies of ignorance.
Jenna Lilla: Fires of knowledge: Ashes of wisdom