How do you know sattva is in charge? Krishna gives a clear diagnostic. When light and awareness flood through every sense — the eyes see clearly, the mind thinks sharply, everything feels vivid and comprehensible — that is the sign.
It is like someone lighting a lamp in a dim room. Suddenly every corner becomes visible. Objects that were vague outlines now have shape and detail. When sattva rises in a person, the senses become alert, perceptions are sharp, and understanding comes easily.
Here, "dvara" (gates) refers to the senses: eyes, ears, nose, and so on. The body is compared to a city with many gates. When sattva is strong, every gate is lit up and functioning at its best.