Bhagavad Gita 2.53
श्रुतिविप्रतिपन्ना ते यदा स्थास्यति निश्चला । समाधावचला बुद्धिस्तदा योगमवाप्स्यसि ॥
śruti-vipratipannā te yadā sthāsyati niścalā | samādhāv acalā buddhis tadā yogam avāpsyasi ||
Translation
When your understanding, perplexed by the texts heard, shall stand unmoved and steady in samadhi, then you will attain yoga.
Reflection
What in you has been moving in response to every text you read, that has not yet learned to stand still?
Read this verse in its chapter: Chapter Two
Acalā buddhiḥ. Immovable understanding. Samādhau, in samadhi. The verse names the moment of arrival from the side of the instrument: when the buddhi, the intellect, stops moving in response to every text it has been confronted by, you have it. Śruti-vipratipannā, perplexed by what has been heard: even scripture's competing voices stop pulling the mind side to side. The yoga is not produced by stillness; the stillness is its mark. This is the picture that prepares the listener for the sthitaprajna description that begins in the next verse.