Matthew Flinders' exploration, circumnavigation and eventual mapping of the Australian continent is a significant part of the country's colonial history.
Yet the workings of the master cartographer have not been seen by the world since Flinders left Australia in 1803.
Two centuries later, the books used as source material by Flinders during his three-year voyage are back on Australian soil, in the possession of the National Archives in Canberra.
"They are unique. These books are internationally significant," assistant director-general for collection management Steven Fox said.
"This is really the first time that the world has actually been able to see this information."
The books themselves — second prints of an edited version of Captain James Cook's Pacific journals — are roughly 250 years old and very rare.
Flinders added his notes in the margins and on the maps, making the books one of a kind.
Mr Fox said Flinders even corrected some of the latitude and longitude measures that Cook had taken years earlier.
"They reveal the way that Matthew Flinders attacked his work," Mr Fox said.
"This is like the primary source of evidence that he collected as he was travelling around Australia."
Early written records of language of Noongar people
Flinders set sail from England in 1801 aboard the HMS Investigator, charged with creating the first full map of the Australian continent.
Flinders is also thought to have been the first person to use the name Australia, as opposed to "Terra Australis".
"This is a really important story in the colonial history of Australia," Mr Fox said.
But he said the books also contained early written records of Indigenous language used in southern Western Australia.
Flinders recorded a short dictionary of the Indigenous language created while on the traditional country of the Minang/Menang Noongar people.
Mr Fox said the National Archives would now consult with First Nations people from the region to establish the significance of the language recorded.
Also included in the collection handed to the archives is a letter written by Flinders in London to his new 13-year-old sister-in-law, Belle.
"Knowing your wish to possess something from New Holland, I have sent you the dried skeleton of a little, comical fish," Flinders writes.
Signed "your affectionate brother", the letter was sent on the eve of Flinders' departure from London in 1801, with a trinket included from a previous voyage.
Collection worth almost $1m donated by philanthropist
The existence of these rare books was not known until they came up for auction last year.
The collection was held by Flinders' descendants in the United Kingdom before being sold by Christie's of London.
From there, the books were purchased by Australian philanthropist Barbara Mason to be donated directly to the archives.
"I've also always believed that if you're lucky enough to have something, you should try and share it with people, to try and give something back that's meaningful to everybody," Ms Mason said.
With the books safely back in Australia after they left centuries ago, Ms Mason is now able to examine them for the first time.
"You look at it and think, 'Oh my goodness, this was actually written by Matthew Flinders in a book that was actually written by Captain Cook'," she said.
Thanks to Ms Mason, others will also be able to see the collection, with the archives restoring and digitising the books and eventually putting them on public display.
Mr Fox said the collection would still be in the hands of private collectors and locked away from public view if not for Ms Mason.
The book sold for 400,000 British pounds ($750,000) and the letter sold for 68,750 British pounds ($129,000) — well out of reach for Australia's national institutions.
"We could not have done it without Barbara's support," Mr Fox said.
"I believe it's an incredibly patriotic act. It's selfless. I mean, she's secured these items. She's donated them to a national collection, really, for the people of Australia."
