Recently I reviewed Our Mathematical Universe, in which Mark Tegmark says that the universe is not just described by mathematics, it is mathematics. So I was interested a couple of days ago to hear BBC's interview with the mathematician Marcus du Sautoy in The Life Scientific. (Du Sautoy is Simonyi Professor for the Public Understanding of Science in succession to Richard Dawkins.) At the end of the interview he talked about the omnipresence of mathematics in science, and said: "I'm becoming more and more a believer in the fact that the universe is a physicalised piece of mathematics . . . The reason that we're seeing mathematics everywhere is that actually the universe is a piece of mathematics."