 By this modified criterion the Precession of Mercury counts as a novel fact with respect to Einstein’s programme. For the General Theory was designed to solve a different set of problems. The prediction that if the General Theory were correct, the perihelion of Mercury would shift as it does without the influence of any other heavenly body came as an “unexpected present from Schwarzschild” (the man who did the sums). It was therefore “an unintended by-product of Einstein”s programme’ (WDCRPSP: 185). So despite its antiquity, the Precession of Mercury counts as a novel fact or a novel prediction with respect to Einstein’s programme, thus making the programme a lot more progressive. Some might regard Zahar’s amendment as a suspiciously ad hoc move, but ad hoc or not, it looks like an improvement on the original MSRP. Lakatos and Zahar go on to use this idea to explain why Copernicus’s programme very properly superseded Ptolemy’s.