य आकाशे तिष्ठन्नाकाशादन्तरो यमाकाशो न वेद यस्याकाशः शरीरं य आकाशमन्तरो यमयत्येष त आत्मान्तर्याम्यमृतः ॥३,७.१२ ॥
In plain words
He who dwells in space, yet is within space, whom space does not know, whose body space is, who from within controls space — he is thy Self, the inner controller, the immortal.