Bhagavad Gita, Chapter 14, Verse 5

Sattva, Rajas, and Tamas, these Gunas, O mighty-armed, born of Prakriti, bind fast in the body the indestructible embodied one.

Three real, distinct forces are named here as what actually keeps the soul tied to the body.

Sattva, rajas, and tamas aren't described as abstract categories, they're named as active forces doing real binding work. Understanding them starts with naming exactly what they do.