The youngest sibling of a whole family of writing tools that arrived in a flurry in the few decades either side of the beginning of the thirteenth century

The index, after all, did not arrive alone, but is rather the youngest sibling of a whole family of writing tools that arrived in a flurry in the few decades either side of the beginning of the thirteenth century. And all have one thing in common: they are all designed to streamline the reading process, to bring a new efficiency to the way we use books.

D. Duncan, Index, a history of the (2021), 56