From the Adhyatma Upanishad

In the cave of the body is eternally set the one unborn. The earth is His body. (Though) moving within the earth, the earth knows Him not. The water is His body. (Though) moving within the water, the water knows Him not. The fire is His body. (Though) moving within the fire, the fire knows Him not. The air is His body. (Though) moving within the air, the air knows Him not. The ether is His body. (Though) moving within the ether, the ether knows Him not. The mind is His body. (Though) moving within the mind, the mind knows Him not. The intellect is His body. (Though) moving within the intellect, the intellect knows Him not. The ego is His body. (Though) moving within the ego, the ego knows Him not. The mind-stuff is His body. (Though) moving within the mind-stuff, the mind-stuff knows Him not. The unmanifest is His body. (Though) moving within the unmanifest, the unmanifest knows Him not. The imperishable is His body. (Though) moving within the imperishable, the imperishable knows Him not. The Death is His body. (Though) moving within Death, Death knows Him not. He, then, is the inner-self of all beings, sinless, heaven-born, luminous, the sole Narayana.