That step, of the form of radiance, the connection being with 'abode' across the intervening words: the sun does not light it up, though it has the power of lighting all; nor does the moon; nor does fire. That abode, the step which is Viṣṇu's, having gone to and reached which they do not return, and which the sun and the rest do not light up, is My supreme step, of which it was said 'having gone to which they do not return' (Gītā 15.6). Now it is well known that every going ends in a coming-back, and that joinings end in partings; how is it said that for those who have gone to that abode there is no return? Hear the reason.

That light of the self the sun does not light up, nor the moon, nor fire. For knowledge alone is the illuminer of all; the outer lights are of use only by way of doing away with the darkness that obstructs the contact of sense and object. And the illuminer of this self is discipline, and what obstructs it is the beginningless karma, and the doing away with that karma was told as rooted in the taking-refuge in the Blessed One, non-attachment and the rest. Gone to which they do not return again, that is My supreme abode, the supreme light, Mine, that is, become My glory, My portion. This is the meaning. By its being the illuminer even of the sun and the rest, it is supreme; for the lights, the sun and the rest, are not the illuminers of the knowledge-light, since knowledge alone is the illuminer of all.

This is a brief sub-gloss. For a fuller reading of this verse, see Madhusūdana, Śaṅkara, or Rāmānuja above.

Krishna tells of His own form, with 'that, which the sun does not light' and so on.