621. Sankhya is understood by the commentator as implying Vedanta-vichara.
622. This verse is a triplet. The commentator explains that Vedanta in the second line means Sankhya. I think, this is said because of the agreement between the Vedanta and the Sankhya in this respect notwithstanding their difference in other respects. The object of the verse is to say that according to the Sankhya, there is no necessity for silent recitation of mantras. Mental meditation, without the utterance of particular words, may lead to Brahma.
623. Both declare, as the commentator explains, that as long as one does not succeed in beholding one's Soul, one may silently recite the Pranava or the original word Om. When, however, one succeeds in beholding one's Soul, then may one give up such recitation.
624. There are two paths which one in this world may follow. One is called Pravritti dharma and the other Nrivritti dharma. The first is a course of actions; the second of abstention from actions. The attributes indicated in 10 and 11 belong to the first course or path. They are, therefore, called Pravartaka yajna or Sacrifice having its origin in Pravritti or action.
625. i.e., he should first cleanse his heart by observing the virtues above enumerated.
626. Samadhi is that meditation in which the senses having been all withdrawn into the mind, the mind, as explained previously, is made to dwell on Brahma alone.
627. The end declared by Bhishma in the previous section is the success of yoga, or freedom from decrepitude and death, or death at will, or absorption into Brahma, or independent existence in a beatific condition.
628. It should be noted that 'hell,' as here used, means the opposite of Emancipation. Reciter may attain to the joys of heaven, but compared to Emancipation, they are hell, there being the obligation of rebirth attached to them.
629. Even this is a kind of hell, for there is re-birth attached to it.
630. Aiswvarya or the attributes of godhead are certain extraordinary powers attained by yogins and Reciters. They are the power to become minute or huge in shape, or go whither soever one will, etc. These are likened to hell, because of the obligation of re-birth that attaches to them. Nothing less than Emancipation or the absorption into the Supreme Soul is the end that should be striven for.