Bhagavad Gita · Chapter 14: The Three Qualities of Nature

Bhagavad Gita 14.23

udāsīnavadāsīno guṇairyo na vicālyate | guṇā vartanta ityeva yo'vatiṣṭhati neṅgate ||

who sits like one unconcerned and is not disturbed by the qualities; who stands firm and does not waver, knowing that it is only the qualities that are acting;

Modern context

'It is only the qualities that are acting.' This short sentence is a whole practice. When anger arises, rajas is acting. When dullness settles, tamas is acting. When clarity shines, sattva is acting. The one who knows this stands firm and does not waver. It is like watching waves from a cliff: they rise and crash, and the cliff does not move.