Tat cchidresu pratyayantarani samskarebhyah

The twenty-seventh yoga sutra explains about the terrible danger of a fissure that can be created in the intermediate period of the path of consciousness towards self-realisation. This fissure can induce enormous troubles and hindrances in the form of restricting one within the worldly temptations and ill-feelings. Consciousness thus can face hurdles towards reaching the seer, by fluctuating moods and modes of thought, all arising because of one`s utter carelessness. It is Patanjali`s solemn advice to the yogis, who wish to be free from the world, to stay continuously observant.

tat that
cchidresu a hole, slit, pore, fissure, defect, rent, flaw, fault, opening
pratyaya going towards, belief, firm conviction, trust, reliance, confidence, content, notion
antarani interval, space, intermission
samskarebhyah from impression

Notwithstanding this progress, if one is careless during the interval, a fissure arises due to past hidden impressions, creating division between the consciousness and the seer.

The force of past impressions may create loopholes in the form of intellectual pride or other varying moods or modes of thought, which breach the consciousness and agitate the harmony and serenity of oneness with the pure Self (atmabhava).

This sutra shows a way to fight old impressions that may influence the consciousness and crack it. Patanjali cautions that even for the supreme intelligence, the subconscious samskaras may surface in this intermediate stage and sway the consciousness.

Patanjali advises yogis who wish to be released from worldly life to be incessantly vigilant in order to overcome these old habits, lest their consciousness wavers between the desire for perfection and actual perfection. The uninterrupted practice of yoga unconditionally crushes these fissures in consciousness, and eliminates doubts and prejudices, so that pure wisdom may shine.

(Consciousness in evolved souls is dealt with in 1.18, wherein the yogi is on the threshold of sabija and nirbija samadhis.)

In the Bhagavad Gita 11.59, Lord Krishna says that inbuilt desire persists as a fissure even in the most austere renunciate. Only the vision of the Supreme resolves these latent faults forever. From that moment no worldly desire or temptation can endanger the composure and virtue of the yogi. (1.50; HI.55-56.)