By which one knows form, taste, smell, sounds, touches and unions; by that same one knows all. What remains here to be known? This is in truth That.

This verse identifies the Ātman as the fundamental knower.

Yena — by which. The instrument of knowing.

Rūpaṃ rasaṃ gandhaṃ śabdān sparśāṃś ca maithunān — form, taste, smell, sounds, touches and sexual pleasures. The five senses plus the pleasure of unions (maithuna).

Etenaiva vijānāti — by this very one one knows. The Ātman is the knowing subject, not the physical senses.

Kim atra pariśiṣyate — what remains here? If the Ātman knows everything through the senses, what else is there to know?

Etad vai tat — this is in truth That. The identity between the individual Ātman and Brahman.

Yoga practices interiorization to contact this knowing principle that underlies all sensory experience.