I went back to get a better look at the cryptic message which turned out not to be so cryptic, but rather poetic. First I wrote it down in my notebook, then I kind of looked over my shoulder to see if people were watching, then I photographed it because I liked the hand writing and the near invisible girl with ear muffs in the picture.
As I put away my camera, a voice called out to me in Dutch 'so what does it say?'. I looked up around and up, and sitting with his feet hanging off the roof of the building on the opposite side of the street was a man who had probably been watching me the whole time.
So I translated it for him: 'To forget a very big sadness, I will kiss you in a spiral... when no one is watching...'. And the man said 'that's very nice' and smiled. I agree with him, its beautiful.