I´ve found the reference concerning " in a glass, darkly" and it is in the Bible, in the Second Epistle of St. Paul to the Corinthians 13:1 and there are several references to the ability to use language and to prophesy.

It begins with " Though I speak with the tongues of men and of angels, and have not charity, I am become as sounding brass, or a tinkling cymbal" [...] For me know in part and we prophesy in part. But when that which is perfect is come, then that which is in part shall be done away. When I was a child, I spake as a child, I understood as a child, I thought as a child: but when I became a man, I put away childish things. For now we see through a glass, darkly; but then face to face: now I know in part; but then I shall know even as also I am known [...]

I´ve checked one of the translations in Portuguese for the New Testament and there the word for glass has been " mirror" !

Through or "in a glass, darkly "? I wonder how it would appear in Nabokov´s Russian Bible, or if it was meant as a quotation anyway.