'And when (it is said that) there (in the Sushupti) he does not smell, yet he is smelling, though he does not smell. For smelling is inseparable from the smeller, because it cannot perish. But there is then no second, nothing else different from him that he could smell.

In plain words: The sage Yajnavalkya explains that in deep, dreamless sleep (Sushupti) a person does not smell anything. Yet the power of smelling is still there and never dies. There is simply nothing separate from him left to smell.