Nico, I like the simplicity and strong use of colour here. I'm assuming it's on a mirror to provide the 'invisible' barrier. I would describe gravity as an invisible barrier along with some other kinds of force, but the one that sticks in mind the most is when mother-in-law was walking out onto a patio in a holiday villa we rented. The glass in the patio door was so clear and clean she didn't see it, but we all heard the bang... Laugh? Me? ;-) -Najinsky
