The example of the watch in William Paley’s Natural Theology (1802) is famous. A stone found on a heath, Paley explains, seems not to require any explanation, but a watch, with its component parts apparently designed to perform a function, demands to be explained, and explained, moreover, in terms of a designer. And the same is true, he argues at length, of living things. Although Paley is sometimes credited with the example of the watch, it is, I think, generally recognized that he was only the latest in a long string of writers to use horology in the service of natural theology: Cicero, in the first century BCE, similarly appealed to sundials and water-clocks in De natura deorum. So Paley wasn’t original. But was he a plagiarist?