In the high-energy magic facility of Unseen University, the wizards have created a miniature cosmos that includes Roundworld, known to us as Earth. As they bicker over the meaning of this - to them - unfeasible and bizarre planet, we go on a tour of Big Science. From astrophysics to quantum mechanics, the interleaved chapters give us a briefing on the history and the present state of play of our scientific learning, while stressing alway the limits of our knowledge–.