'He who dwells in the skin, and within the skin, whom the skin does not know, whose body the skin is, and who pulls (rules) the skin within, he is thy Self, the puller (ruler) within, the immortal.'

In plain words: Yagnavalkya says something lives inside the skin, the sense of touch, and guides it from within. The skin does not know it. That inner guide is your undying Self.