The Butler Act, outlawing the teaching in Tennessee’s public schools of “any theory that denies the divine creation of man and teaches instead that man has descended from a lower order of animals,” became law on March 21, 1925. But it really wasn’t a matter of national interest until May 1925, when, in short order, John Thomas Scopes agreed to become the defendant in a case testing the law’s constitutionality, William Jennings Bryan and Clarence Darrow agreed to join the legal teams representing the prosecution and the defense (respectively), and Scopes was duly indicted. That was enough to kindle interest in the issue of teaching evolution around the country. And my choice of the particular verb “kindle” is deliberate.

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?