There is a piece of rubbish among the treasures on display in the British Museum’s new exhibition “Egypt: faith after the pharaohs” (until 7 February). It is a wodge of crumpled paper from the genizah or sacred storeroom of the Ben Ezra Synagogue in Old Cairo.Found in 1896 it contains a cache of 200,000 untouched documents – from shopping lists to works of philosophy – that are still yielding insights into the daily lives of Jews in Egypt from the eleventh to the thirteenth centuries. Egypt’s arid climate has made it a paradise for archaeologists and, like the genizah, this exhibition is a time capsule of miraculously preserved objects – from shreds of manuscripts in Greek, Latin, Coptic, Arabic and Hebrew to a child’s stripy sock – th