Plato I know, or at least I thought I did. But a Googleplex? I had no idea. I had heard of a googolplex, which is a really large number, allegedly described by its inventor – a nine-year-old boy – as ‘one, followed by writing zeroes until you get tired’. I had also heard of a multiplex – a cinema with a lot of screens. So I thought perhaps a Googleplex was a cinema with so many screens that simply finding the one showing your film made you tired. I was wrong. The Googleplex is the headquarters of Google in Mountain View, California. But my ignorance about this crucial contemporary reference point helped me to identify with the figure of Plato in Rebecca Newberger Goldstein’s wonderful new book, which teleports the unwitting ancient philosopher into the modern world. It also turns out that I was wrong in thinking I knew Plato, as Goldstein’s brilliant study shows him in a whole disco of new lights.