The Upanishads, Part 1 (SBE01), by Max Müller, , at sacred-texts.com
THE Vâgasaneyi-samhitâ-upanishad, commonly called from its beginning, Îsâ or Îsâvâsya, forms the fortieth and concluding chapter of the Samhitâ of the White Yagur-veda. If the Samhitâs are presupposed by the Brâhmanas, at least in that form in which we possess them, then this Upanishad, being the only one that forms part of a Samhitâ, might claim a very early age. The Samhitâ of the White Yagur-veda, however, is acknowledged to be of modern origin, as compared with the Samhitâ of the Black Yagur-veda, and it would not be safe therefore to ascribe to this Upanishad a much higher antiquity than to those which have found a place in the older Brâhmanas and Âranyakas.
There are differences between the text, as contained in the Yagur-veda-samhitâ, and the text of the Upanishad by itself. Those which are of some interest have been mentioned in the notes.
In some notes appended to the translation of this Upanishad I have called attention to what seems to me
its peculiar character, namely, the recognition of the necessity of works as a preparation for the reception of the highest knowledge. This agrees well with the position occupied by this Upanishad at the end of the Samhitâ, in which the sacrificial works and the hymns that are to accompany them are contained. The doctrine that the moment a man is enlightened, he becomes free, as taught in other Upanishads, led to a rejection of all discipline and a condemnation of all sacrifices, which could hardly have been tolerated in the last chapter of the Yagur-veda-samhitâ, the liturgical Veda par excellence.
Other peculiarities of this Upanishad are the name Îs, lord, a far more personal name for the highest Being than Brahman; the asurya (demoniacal) or asûrya (sunless) worlds to which all go who have lost their self; Mâtarisvan, used in the sense of prâna or spirit; asnâviram, without muscles, in the sense of incorporeal; and the distinction between sambhûti and asambhûti in verses 12-14.
The editions of the text, commentaries, and glosses, and the earlier translations may be seen in the works quoted before, p. lxxxiv.