Cornish translation of Bible's Old Testament
Cornish speakers can now read the complete Bible - An Beybel Sans - in their chosen language.
The New Testament was translated into Cornish by Prof Nicholas Williams and published in 2002.
It has taken him about six years to translate all the books of the Old Testament, using a variety of versions, including Hebrew and Greek texts.
An Beybel Sans is written in standard Cornish and its 10 maps also have place names in Cornish.
The 69-year-old professor from London, who is considered to be one of the leading experts on Celtic languages, taught himself Cornish at the age of 15 because it seemed "a bit odd and a bit bizarre".'Boring bits first'
He told BBC Radio Cornwall: "One of the reasons we lost the language was because there was no Bible in Cornish.
"The Welsh had one (in Welsh) from the time of Elizabeth I, but the Cornish didn't.
"As well as being the Hebrew and Christian Scriptures it is one of the defining books of our culture.
"Once you have the Bible you have created your literary heritage and I hope this book will be influential in the Cornish revival."
Prof Williams, who also taught Irish Gaelic at University College Dublin for 30 years before retiring, said he kept going on the marathon task by doing the "boring bits first" - starting with Leviticus, the chapter of the Old Testament which deals with which foods people can eat.
The last speaker of Cornish as a first language is believed to have died more than 200 years ago.
It was recognised as a language by the UK Government in 2002, but deemed "extinct" by the United Nations (UN) in 2009, to the anger of many in Cornwall.
However, last year it was reclassifed as "critically endangered" by the UN.
The language has been undergoing a revival in its native lands, with dual-language road signs an increasingly common sight.
In January 2010 a creche teaching young children the language was opened.