More than 100 letters and a sketch by prominent New Zealand artist Colin McCahon have been given to the Hocken Library.
The letters and artwork were donated by John and Andrew Parsloe, nephews of McCahon.
Andrew Parsloe said his parents Noel and Beatrice Parsloe had stipulated in their wills the collection be donated to the Hocken Library.
Most of the letters were addressed to his mother, McCahon's sister, he said.
"My mother was aware from a very early age that keeping those letters would be important.
"From the beginning she was a strong supporter of Colin and his art.''
The first letter in the collection was written by McCahon to his father in 1926, while the last was addressed to McCahon's sister in 1982, he said.
The letters offered "illuminating'' insights into McCahon's total dedication to art, and the deterioration of his health in the lead up to his death in 1987, he said.
"Some of the letters reveal a fair amount of passion about choosing painting as a vocation and not being distracted by secondary things, sometimes perhaps even family.''
It was evident in the letters when McCahon was busy working on a project because the letters would be short and scrappy, he said.
A sketch of a Mrs Scott, of Ruby Bay, drawn in 1939 was discovered enclosed in one of the letters, and was now part of the Hocken collection.
In the letter accompanying the sketch McCahon writes "Please don't keep this drawing unless you especially want to.
"I'm not at all satisfied with it ...''
John Parsloe said he had strong memories of spending time with his uncle in the 1960s, salvaging objects from the dump and hearing his strong opinions delivered to other notable artists of the time.
Hocken Library curator of archives and manuscripts Anna Blackman said the collection was a "wonderful addition'' to the archives.