But not all his interviewees were patients in asylums. "Patients in asylums made up only 10 percent of my interviewees. Most of the patients lived at home and the others are what we call 'unusual' people. They just see the world differently. I still keep contact with some of them," he says.
Gao talked to more than 100 patients and "unusual" people in cities across the country from 2003 to 2008.
Sometimes he went to those cities on business trips, but in many cases he went specially to visit his interviewees.
In early 2008, after about 200 interviews, Gao had a feeling of "fullness". He stopped the project and went back to his normal life.
In 2009, after three exhausting months of his regular job, Gao took a vacation.
"I didn't feel relaxed after a month's vacation. My brain was working at a high speed. I wanted to do something, and it was the time," he says.
At 2:30 am on Aug 17, Gao typed the first character on the Tianya Forum online, and in 38 days 220,000 characters had been typed.
"I didn't find similar stories on the forum, so I just posted them under the category of 'ghost' stories. I did not care whether readers would believe them or not," he says.
The stories were very popular, and soon more than 20 publishers came to him to talk about compiling them into a book. In 2010, the first edition of the book came out and about 2 million copies have been sold so far, according to OpenBook, an industry-data provider.
Some people question whether his stories are true and whether they violate people's privacy.
"I asked permission from the guardians, and many of the patients were conscious of their situation. I didn't mention any names or backgrounds. And I just wrote down dialogues that I think are inspiring, and sometimes if I found two or three interviewees talking in a similar fashion, I combined their stories into one, like in the case of the boy talking about four dimensional spaces," he says.
The 10 new stories in the second edition were already on Tianya.
"I didn't understand many things six years ago when I wrote the stories."
But now, after many other experiences: "I can understand what they meant by the universe with Eight Diagrams (for practicing divination)".
"You can see how colorful the world is when you see it from a different perspective. I hope readers will give up their prejudices about the world and embrace it with an open heart after reading my stories," he says.
