The Imperishable (akṣara), that which does not perish, is the supreme Self, by the scripture 'at the command of this Imperishable, O Gārgī' (Bṛhadāraṇyaka 3.8.9). The syllable Om is not what is meant here, since it is later marked off by a further qualification, 'Om, the one-syllabled Brahman' (Gītā 8.13); and the word 'supreme' is the more fitting qualification for the Imperishable that is Brahman, beyond which there is none higher. The very own being of that supreme Brahman, its presence in each body as the inmost Self, is called the 'adhyātma': the thing which, taking the body, the self, as its base, proceeds as the inmost Self and ends in the Brahman that is the supreme reality, that own being is the adhyātma. The 'bhūta-bhāva-udbhava-kara' is the maker of the coming-to-be of beings: the becoming of beings is the bhūta-bhāva, its arising is the bhūta-bhāva-udbhava, and that which brings this about is the maker of it. 'Visarga' is the letting-go, the relinquishing, with a deity in view, of a substance such as the oblation-cake; that very thing, marked as a letting-go, is the sacrifice, named 'karma', action. From this, which is the seed, beings moving and unmoving arise through the sequence of rain and the rest.
Contemporary English rendering of the Sanskrit bhāṣya, pending scholar review.