The language of mathematics

‘I find that the earth is not as round as it is described, but it is shaped like a pear,’ Christopher Columbus wrote after his return from America, ‘with a woman’s nipple in one place, and this projecting part is highest and nearest heaven.’

Determining the shape of the surface on which we live is, as Donal O’Shea observes in this historically minded little book, a delicate matter. Columbus’s idea was not (at least, not only) the lascivious fantasy of a hoary sea dog. He believed that he had reached India, not America. But he also knew that he had completed the journey much more quickly than the accepted size of the world allowed: the well-travelled southern route suggested Asia was thousands of miles further away. A mammary planet, God-seeking nipple northward, was the only explanation. Even after Ferdinand Magellan returned from his circumnavigation in 1522, it wasn’t (as O’Shea, who is pernickety as well as entertaining, remarks) clear that Earth was a sphere.