The Moebius strip was a gift from college mathematics, one of its surprises. The old children's magic trick that we used to do by cutting lengthwise a paper ring obtained after turning and gluing the ends of a ribbon, and that miraculously managed to reproduce the whole ring or two chained rings, turned out at university to be nothing less than a topology scientifically enunciated by a certain Moebius. A surface that extends - how? - by its own underside. He had the name of a morbid savant and we never knew who he was, because at school those who enunciated principles and theorems, like Gauss or Hooke, seemed to be beings from out of the world and out of time?..[+]