A version of the first Welsh language bible has appeared online 400 years after the death of the bishop who first translated it.
Digitisation is ushering in a revolutionary period in the way the library works, say officials
William Morgan's book is claimed to be the most important ever published in Welsh as it reinforced the language's status.
The National Library of Wales, in Aberystwyth, has added its 1,110 pages to its website.
Morgan, from Conwy, who was Bishop of Llandaff and later of St Asaph, died on 10 September 1604.
Lyn Lewis Dafis, metadata manager at the library, said publishing the national treasure had been "a challenge."
"By using the latest technology the work has been completed successfully and was well worth the effort.
"When the bible was originally published it marked a revolution in the status of the Welsh language.
"Digitisation is ushering in a revolutionary period in the way the library works today and its only fitting that a volume of such immense influence should also be part of this new revolution.
"I very much hope that all the users of our website, especially school and college students, will take advantage of the opportunity to be able to turn the pages of William Morgan's bible for themselves."
The bible is credited with sustaining the Welsh language in the face of official neglect and animosity, said the National Library.
Bishop Morgan translated the bible into Welsh from Hebrew and Greek
After studying Hebrew, Greek and Latin at Cambridge University, Bishop Morgan translated the bible from Hebrew and Greek originals, also using Salesbury's New Testament and the English bishops' and Geneva versions.
"The translation of the bible into Welsh was a result of a measure passed in Parliament in 1563 authorising the translation of the bible and the Book of Common Prayer," said John Watts-Williams, head of digitisation and retro-conversion at the National Library.
"It was anticipated that the translation would be complete by St David's Day in 1567, however only the New Testament and the prayer book were ready in that year.
"It was through the labours of William Morgan, who appears to have taken it upon himself to undertake the huge task in about 1578, that the work was eventually completed, with the publication of the complete translated bible in 1588."
The library has also digitised Dr Prys Morgan's book, A Bible for Wales.