Brahma Knowledge, by L. D. Barnett, [1911], at sacred-texts.com

§ 14. Parmenides.—The opportunity here presents itself to point to the singularly close parallel between Upanishadic thought and the doctrines of the early Eleatic philosophers, and especially Parmenides, who may well have been contemporary with the authors of some of the most important Upanishads. Following Xenophanes, who had defined God as eternal, one, and neither in motion nor immobile, Parmenides asserts a single universal Being which is identical with thought. Existence is a whole indivisible in space and time; non-being does not exist. "Thus there remains but one way to tell of, namely that Being is. There are many tokens to show that it is unborn and imperishable, whole, only-begotten, unshakeable, and endless. Never was it nor will it be, for it exists entirely in present time, one and indivisible… Thus it must exist either absolutely or not at all. The power of belief can never admit that from non-being anything else (but non-being) could arise… And it (viz., being) is not divisible, for it is identical throughout; nor is there any higher (being) that could prevent its uniformity, nor any less; it is entirely full of being. So it is wholly uniform, for being unites with being. But it is immobile in the limitations of mighty bonds, beginningless

p. 35

and endless; for birth and destruction have been driven very far away, right conviction has rejected them. It abides the same in the same and by itself, and thus remains constantly in its place… Thought and the object of thought are the same, for you cannot find thought without the existent thing in which it is expressed. There is and can be nothing except being, for fate has bound it down to be whole and immobile. Thus all (ideas) that men have set up, believing them to be true—birth and death, being and non-being, change of place, and alteration of bright hue—are mere words" (fragment 8, ed. Diels); cf. fragment 5, "thought (of being) and being are the same," fragment 6, "speech and thought must be real, for being exists and a naught does not exist," fragment 7, "non-being can never be proved to exist." Except in his view of Being as a sphere, Parmenides is in perfect accord with the Vedānta. The similarity of Plato's doctrines is well known.