I have worked on the sentence: “Set your mind before the mirror of eternity!”
What I do understand is that Clare gave me a glimpse of the peace and quiet the mirror of eternity can bring if I set my mind (full of worries) before the mirror. I see Clare as the angel Gabriël with the message. If I am Mary on the card getting the message, I do not understand why I turn my head, because I really liked that glimpse. So, hmmm. I do not know.