Bhagavad Gita Chapter 6, Verse 19

यथा दीपो निवातस्थो नेङ्गते सोपमा स्मृता | योगिनो यतचित्तस्य युञ्जतो योगमात्मनः ||

yathā dīpo nivāta-stho neṅgate sopamā smṛtā yogino yata-cittasya yuñjato yogam ātmanaḥ

As a lamp in a windless place does not flicker, so is the yogi whose mind is controlled, practicing union with the Self.

Krishna uses a beautiful metaphor to describe the steadiness of a yogi's mind. 'Yathā dīpo nivāta-stho neṅgate'—as (yathā) a lamp (dīpaḥ) in a windless place (nivāta-sthaḥ) does not flicker (neṅgate). This means: when a lamp is protected from wind, its flame is steady, unwavering, constant. There's no disturbance, no flickering, no movement—just steady light. 'Sopamā smṛtā'—that (sā) comparison (upamā) is given (smṛtā). This means: this is the analogy to remember. 'Yogino yata-cittasya yuñjato yogam ātmanaḥ'—of the yogi (yoginaḥ) whose mind (cittasya) is controlled (yata), practicing (yuñjataḥ) yoga (yogam) with the Self (ātmanaḥ). This means: the yogi whose mind is controlled, who practices union with the Self, has a mind that's like that steady lamp—unwavering, undisturbed, constant. The controlled mind doesn't flicker—it's steady, focused, peaceful. This is the result of proper practice—mind becomes steady like a lamp in a windless place.