Bhagavad Gita Chapter 2, Verse 53
श्रुतिविप्रतिपन्ना ते यदा स्थास्यति निश्चला । समाधावचला बुद्धिस्तदा योगमवाप्स्यसि ॥
śruti-vipratipannā te yadā sthāsyati niścalā | samādhāv acalā buddhis tadā yogam avāpsyasi ||
When your intellect, confused by hearing many teachings, stands steady and unmoving in samadhi, then you will attain yoga.
Arjuna has heard conflicting teachings about duty—his intellect is 'śruti-vipratipannā' (confused by many heard teachings). Krishna reveals the marker of yoga: when your 'buddhi' becomes 'niścalā acalā' (unwavering, unmoving) 'samādhau' (in absorbed clarity), then you attain yoga. First you cross confusion's forest (2.52), then your clarity becomes steady. 'Samādhi' isn't mystical—it's when your mind stops scattering with every input and rests in integrated understanding.