Blush

Why does Mary blush? I have not seen a blushing Mary before. But there is a first time for everything.
Extra: 16th century graffiti on the backside of an altar piece / reredos.
Second extra: We had our picnic in a nunnery ruin.  And the fika we had at a churchyard...... again. I am used to it now and do not feel uncomfortable. I definitely do not blush.