स्वमनोमननं तन्तुर्मनोभ्यासेन यत्नतः ।विचाराच्छेदमायाति च्छिन्नैवाज्ञानभावना
In plain words
The thread is the thinking of one's own mind. By the mind's steady practice, with effort, through vicāra, it comes to be cut — and cut indeed is the imagining born of ajñāna.