In early 1973, a team of workers who were renovating the Grand Mosque of Sanaa in Yemen came upon a hidden trove of manuscripts between the ceiling and the roof. Reduced to fragments, the books had become unusable and were abandoned, probably after the reorganisation of the mosque library. While a German-Yemeni team was cataloguing and restoring the tens of thousands of manuscript fragments in the 1980s, they found a unique manuscript – a palimpsest – that almost certainly dates from the first century of Islam. “The most unusual feature of the Sanaa manuscript is that both texts – the original…