The three qualities of nature: sattva, rajas, tamas.
Triguna holds that everything — matter, mind, food, mood — is woven from three strands: sattva (clarity, balance), rajas (activity, restlessness), and tamas (inertia, heaviness). Nothing is purely one; each thing is a proportion, and to change something is to shift its blend.
Triguna unlocks classification by tendency rather than substance: instead of asking what a thing is made of, you ask which qualities dominate it. It gives a single vocabulary that spans the physical and the psychological, letting a meal, a mind, and a moment all be read on the same three-way scale.