। ॥ ६४७ ॥
In plain words
But when sattva is what rules this mind, then it is the Self alone that shows up reflected there — the Self whose mark is ānanda, sheer bliss — the way the moon appears in clear water.
Close to the Sanskrit
But in this mind, in which sattva predominates, the Self alone — whose mark is bliss — is reflected, as the moon in clear water.