cum isto gemino obtūtu (aspexi)
I saw [sth] with my own eyes
Metamorphoses (Apuleius), I, 4
Funny that in Portuguese, we have a saying "este é irmão deste" (this one is the brother of this other one), concerning the eyes, but the meaning is different, it means "I'm very aware of what is going on", in a sense that whatever is going on is not enough to deceive the person who says the saying.
Anyway, I guess it's expected to treat eyes as brothers, specially twins, in the case of the Latin idiom used by Apuleius...