A story from the tradition of the Desert Fathers:

Abba Lot came to Abba Joseph and said:

‘Father, according as I am able, I keep my little rule, and my little fast, my prayer, meditation and contemplative silence; and, according as I am able, I strive to cleanse my heart of sinful thoughts: now what more should I do?’

The elder rose up in reply and stretched out his hands to heaven, and his fingers became like ten lamps of flame.
He said: ‘Why not become completely fire?’