Y Beibl Cysegr-lan (the Welsh Bible) (William Morgan, First printed 1588; the copy linked here is an 1882 printing). William Morgan translated the whole Bible into Welsh in a remote parish, and the prose he wrote did for Welsh what Luther's did for German: it fixed a literary standard and gave the language a reason to survive the centuries in which it had no state and little status. Welsh is spoken today in part because this book existed and was read aloud every week.