I was thinking it would be good to be able to specify a particular piece of music or sound to be played when a particular piece of text was being read in a book. Then I realised that ebooks on tablets make that feasible. In fact why stop at sound – there could be pictures or video associated with particular pieces of text. It would just be a matter of being able to specify the exact location of a piece of text on the screen when such additions start and stop or appear and disappear. Whether this would be a useful adjunct to reading is something that would have to be explored, as, no doubt, somewhere, somebody has done or is already doing – some ideas (like google glass) are just too interesting to some people to not find out they don’t work.