Cheng managed to buy a full set recently from an American family who were among the original subscribers at the time. Surprisingly for a gallerist, Cheng says this is his first serious art purchase.

“It is the greatest photography project of all times. I jumped at the chance to  buy the whole portfolio,” he says, as he gingerly leafs through the precious sepia prints still held in the original envelope. Only a small selection from among the 700-plus prints will be on show, and they are not for sale.

Cheng says he will deliberately avoid some of the more well-known images, such as Geronimo’s weatherbeaten face, in order to present an exhibition that focuses on Curtis’ skills as an artist. He has also commissioned Italian musician Valerio Tricoli to create a sound backdrop to the exhibition.

Curtis died forgotten and destitute, and his place in photographic history remains controversial because of the way he staged the shots for the “The North American Indian” series. His models were not “noble savages” untouched by development, but poverty-stricken, marginalised members of society who had long adopted modern American clothes. The nostalgic, romantic images of a proud people were his own creations and he often paid the native American models to don traditional costumes and to look the part. These were not so much photographic trophies as an abuse of what Susan Sontag described as an assumption of veracity that is associated with photography.

It could have been white guilt, or it could have been a lust for adventure. But Cheng believes that whatever personal reason it was that drove Curtis to go on his epic journeys does not detract from his achievement as an artist.

“The photographs are problematic from an ethnographic or anthropological point of view, but I am most interested in the artist Curtis,” Cheng says. “The images are magical. And it was really interesting the way he blurred dream and reality, fact and fiction,” he adds. To be fair to Curtis, Cheng believes the American public at the time were fully aware of the reality of native American life and would have known that Curtis was presenting a part fiction.

“In my opinion, thank God he did it that way. Otherwise, they would have been photographed in modern clothes, their culture already lost, and beaten down by modern life. Instead, we see them triumphant and proud,” Cheng says. The works also have historic value because they are records of genuine traditional costumes and rituals of the time, he adds.

Cheng, son of former Central Policy Unit head Dr   Edgar Cheng Wai-kin   and the grandson of the late shipping tycoon Pao Yue-kong, has Hong Kong roots but grew up in the United States. He was not particularly interested in native Americans as a boy and only grew to appreciate Curtis’ works when he was studying photography at Harvard University. His Berlin-based publishing company will issue a monograph on the photographer later this year.

Cheng says the collection is relevant to Hong Kong today as a reminder of what we have sacrificed for our way of life.

“The world that he described was one where there was harmony with nature. Now, it’s all about harmony with technology,” he says.

Edward S. Curtis: The man who sleeps on his breath, The Empty Gallery, 19/F, Grand Marine Industrial Building, 3 Yue Fung Street, Tin Wan, Hong Kong, November 7, 2015 – February 6, 2016