For just as different rivers enter the ocean and their names and forms are lost in it, so the sixteen parts of a man sink into the godhead and he becomes without parts and immortal (_Pracna Up_.6.

5); a purely pantheistic view of absorption, in distinction from the Vedic view of heaven, which latter, in the form of immortal joy hereafter, still lingers in the earlier Upanishads.
It is further to be observed as the crowning point of these speculations that, just as the bliss of emancipation must not be desired, although it is desirable, so too, though knowledge is the fundamental condition of emancipation, yet is delight in the true a fatal error: "They that revere what is not knowledge enter into blind darkness; they that delight in knowledge come as it were into still greater darkness" (_Ic[=a]_, 9).

Here, what is not real knowledge means good works, sacrifice, etc.

But the sacrifice is not discarded.
To those people capable only of attaining to rectitude, sacrifices, and belief in gods there is given some bliss hereafter; but to him that is risen above this, who knows the ego (Spirit) and real being, such bliss is no bliss.

His bliss is union with the Spirit.
This is the completion of Upanishad philosophy.