The Noosa-based art collectors have spent the past 40 years travelling the globe acquiring the unusual and the lovely, anything that captured their eye, as long as the piece spoke to them in some way.

But since the early 1990s it has been Australian indigenous art that resulted in that ''thud'' the Clarkes always look for before buying.

Today, in what is being billed by Mossgreen Auctions as one of ''the most significant private collections of indigenous artworks'' to be made available to the market, the Clarkes hope others find the same enjoyment.

The collection of 188 works, which includes major work by Emily Kngwarreye, Tommy Watson and Billy Thomas, represents a rare chance for buyers to own a piece of the Australian story.

Mr Clarke said it was the ''sincerity'' of indigenous art that originally captured his and his wife's eye and resulted in the couple shifting their focus from collecting European art to something closer to home.

''The paintings vary but so many of them tell stories, most of which we would not understand, but they reveal stories that are very, very important to the Aboriginal people,'' he said.

''The vitality is fantastic. It depends on one's eye, but when you are a collector, you collect either because of the story behind the painting, or the painting itself. A lot of people collect so the story behind the painting becomes more important than the painting itself, while others might say, 'I'm not interested in progressing the story in this matter because the painting doesn't mean a thing to me.'''

Paraphrasing an American art critic, Mr Clarke said ''you have to see them and believe rather than believe and see'' when it came to many art works.

''Reducing it to colloquial terms, unless it gives you a thump, well then, don't worry about the story, but if it gives you a thump, then do pursue the story, because there are amazing stories behind Aboriginal art.''

The Clarkes travelled to many of Australia's remotest communities in the Northern Territory and Western Australia and met many of the artists to aid in their understanding of the art.

''I didn't do that to buy from them, I never bought from artists directly,'' Mr Clarke said. ''I bought from the art centres, or in some cases some outstanding art dealers … I was there because I loved doing it, meeting them, seeing it.''

Valued between $1.5 million and $2 million, the collection has amassed strong interest ahead of today's auction.

Mr Clarke said he had retained some favourites, but he said he hoped others garnered the same enjoyment from the collection as he and his wife had.

''Life moves on and I am 72 now,'' he said.

''I should be light on my feet.

''Seeing the whole collection laid out and I think Mossgreen have done an extraordinary job with the lay-out, it was wonderful to see it like that, all laid out together.

''But it is time to move on.''