He replied: "O Gârgya, As all the rays of the sun, when it sets, are gathered up in that disc of light, and as they, when the sun rises again and again, come forth, so is all this (all the senses) gathered up in the highest faculty (deva) the mind. Therefore at that time that man does not hear, see, smell, taste, touch, he does not speak, he does not take, does not enjoy, does not evacuate, does not move about. He sleeps, that is what people say.

In plain words: The teacher explains with a picture of the sun. When it sets, all its rays gather back into it, and when it rises, they shine out again. In the same way, during sleep all the senses gather into the mind, so the person does not see, hear, speak, move or feel, and we say he is asleep.