The next year, he came across a very good introductory book on philosophy in the library and was eager to translate it into Chinese.

He then reached out to a contact at a publishing house, and after writing proposals he was allowed to take up the translation project.

The book, The Big Questions, was reprinted several times and got good feedbacks from readers.

Zhang says his eagerness to share good things with others is his biggest motivator.

"When I read about things that stun me with their genius and perfection, I think I shouldn't enjoy them alone. There must be others who are also interested in and will appreciate them the way I do," he says.

He also understands that his books may be too technical for most readers. And he jokes that he is picky about his readers. But he says that it is still good to be able to "enjoy a spiritual connection with a small number".

While his name is occasionally noticed by readers and few people know who he is, Zhang says that this special existence is "cool", although he does care about his reputation.

According to Zhang, persistence has played a key role in helping him translate so many books over the years.

"Just like walking, you need to make only a little effort for every step. The hard part is never to stop taking small steps, and then you can walk long distances," Zhang says. Yet, there were times when he found it hard to move along.