Besides Laura Cumming's brilliant Thunderclap, I'm reading the fascinating How Dead Languages Work, by Coulter George. In the section on Sanskrit, he says that [Rig] Veda, which means "knowledge," goes back to a root ... that [resembles] its cognates in orther Indo-European branches, such as wit in Engligh and videre "see" in Latin. In earlier English, wit referrred more widely to the intellectual faculties, and to know something, in the metaphor of the parent language was to have seen it.
Laura Cumming writes: The connection between mind and eye is always there: I see, we say, in acknowledgement of a truth, a fact or an explanation. To see is to know. We see the mind in the eye.