Verse 4.26
तदा विवेकनिम्नं कैवल्यप्राग्भारं चित्तम् ॥२६॥
tadā viveka-nimnaṃ kaivalya-prāgbhāraṃ cittam ||26||
Then bent on discriminating the mind attains the previous state of Kaivalya (isolation).
When the exalted intelligence is ablaze, mind is illumined; it becomes free and tinged with the divine (citta suddhi) . Due to this divine light, citta, with its exalted intelligence, is drawn as if by a magnet towards its source: the indivisible seer who is alone, free and full.
Before reaching the state of exalted intelligence, mind is attracted more towards the pleasures of the world. When intelligence is free from doubts and prejudices, it gravitates towards the absolute seer.
As a farmer builds dykes between his fields to regulate the flow of water, exalted intelligence builds a dyke for the mind, so that it does not move again towards the world, but turns and flows towards union with the divine seer. This is kaivalya, an existence filled with freedom and beatitude. Such a yogi becomes a king amongst men.
PATANJALI YOGA SUTRAS