The works of Ādi Śaṅkarācārya

Ātmabodhaḥ

Verse 43

एवमात्मारणौ ध्यानमथने सततं कृते ।उदितावगतिर्ज्वाला सर्वाज्ञानेन्धनं दहेत् ॥ ४२ ॥

In plain words

So: the Self is the block of wood, meditation is the drilling. Keep at it without a break. Knowledge flares up like flame — and every last stick of ignorance is its fuel.

Close to the Sanskrit

Thus, in the Self as the fire-drill block, when the churning that is meditation has been done continuously, the arisen flame that is knowledge would burn all the fuel of ignorance.