It means one's visual memory or imagination and probably became known through the work of Shakespeare. But the concept of us having an 'eye in our mind' dates back to at least the fourteenth century. Nevertheless it was Hamlet who used the phrase in 1603 and established it in everyday language.

Übersetzung:

im Geiste, vor dem geistigen Auge

Gegenteil(e)

The opposite of "in one's mind's eye" is "in reality".

Synonym(e):

You could also say: in one's imagination.