this it follows that the word 'light' here denotes Brahman. 25. If it be objected that (Brahman is) not (denoted) on account of the metre being denoted; (we reply) not so, because thus (i.e. by means of the metre) the direction of the mind (on Brahman) is declared; for thus it is seen (in other passages also). We now address ourselves to the refutation of the assertion (made in the purvapaksha of the preceding Sutra) that in the previous passage also Brahman is not referred to, because in the sentence, 'Gayatri is everything whatsoever here exists,' the metre called Gayatri is spoken of.--How (we ask the purvapakshin) can it be maintained that, on account of the metre being spoken of, Brahman is not denoted, while yet the mantra 'such is the greatness of it,' &c., clearly sets forth Brahman with its four quarters?--You are mistaken (the purvapakshin replies). The sentence, 'Gayatri is everything,' starts the discussion of Gayatri. The same Gayatri is thereupon described under the various forms of all beings, earth, body, heart, speech, breath; to which there refers also the verse, 'that Gayatri has four feet and is sixfold.' After that we meet with the mantra, 'Such is the greatness of it.' &c. How then, we ask, should this mantra, which evidently is quoted with reference to the Gayatri (metre) as described in the preceding clauses, all at once denote Brahman with its four quarters? Since therefore the metre Gayatri is the subject-matter of the entire chapter, the term 'Brahman' which occurs in a subsequent passage ('the Brahman which has thus been described') must also denote the metre. This is analogous to a previous passage (Ch. Up. III, 11, 3, 'He who thus knows this Brahma-upanishad'), where the word Brahma-upanishad is explained to mean Veda-upanishad. As therefore the preceding passage refers (not to Brahman, but) to the Gayatri metre, Brahman does not constitute the topic of the entire section.