Saw two girls who must have been about twelve on the tube talking in sign language. It was really beautiful to watch. Their hands were dancing about like doves. It was all very graceful and they were making each other laugh in silence. I've never really properly seen sign language before. It's quite beautiful. A language traced in the sky. Like trying to write on water with a stick. The words disappearing instantly into the ether. Invisible words gone but leaving a residual trace in those who speak them. The two girls were creasing up. Laughing at some absurd message contained within the elegance of their gestures. An undetectable joke were it not for their laughter and smiling. Like wind invisible save for the observable effect it has on the environment. One day science might seek to eliminate all deafness and this beautiful language could be lost like so many other endangered and extinct languages.