Morck never taught the art prior to his work in China. "It took me 10 seconds to realize that I love teaching! It's 100 percent joy to teach here," Morck says.

His students are also relishing every minute of his lessons.

"He is a very strict teacher but we love him very much," says Yuan Yishan, a student from the Academy of Art and Design at Tsinghua University.

Still, the learning process is "very painful" for many of the students. Morck says one piece of work can take months; sometimes they need to sit up for four or five hours a stretch. Yang Zhiying, another student sitting at the front of the classroom, says her wrist and neck have been in pain ever since the class started. And because there is so much to learn from Morck, Yang, like everyone else, always stays on in the classroom from 8 am to 9 pm to learn as much as possible.

"Students should understand that it's still a long way to go if they want to master this art," Pingel says. It takes five to eight years of practice and the skill of engravers generally peaks when they are in their 40s, he says.

The students are making slow and steady progress, Morck says. More of their work is being displayed on the classroom wall.

"We are very grateful to have him as our teacher and he really helps us grow. There was a real lack in knowledge before he arrived," says Hao Ou, the most experienced student in class. Hao is a third-generation engraver in China and is learning from Morck to refine her skills.

China has a history of more than 100 years of engraved stamps, Hao says. The engraving knowledge she learned was passed down from 1908, when Lorenzo J. Hatch, an engraver for American Banknote Company in New York, came to China and trained several Chinese engravers. But the few old engravers are all above 60 years old and they have stopped engraving because of their age.

One difference between the engravers who taught Hao before and Morck, as she recalls, is that Morck stresses a lot on cultivating the engraver's heart and mind, not just the skills.

"You must be very slow and patient," Morck says at every class.

To help students achieve a peace of mind needed for the work, Morck even reads poetry for his students. His favorite line is "to see the world in a grain of sand, and a heaven in a wild flower", from The Auguries of Innocence by William Blake.

"You can discover a world of stories from a piece of stamp, just like you can see the world from a grain of sand," Morck says.

What he teaches in China is what he has experienced his whole life, Morck says. "I just open my heart and let my experiences out."

Morck himself is a "free spirit". He comes from an artistic family and grew up in his parents' studio.

China Post and Post Denmark have jointly issued a series of stamps on ancient astronomical instruments, engraved by Martin Morck.

"I managed to spend nine years in school and I quit when I was 16 because I couldn't stand it," he says.

Morck fell in love with engraving when he was in art school but there "wasn't enough to learn". At the age of 18, he wrote a letter to the Swedish Post asking them whether it was possible for him to spend some time there to learn postage stamp engraving.

"I had no idea about engraving post stamps," he says. He just found out that the only ones who knew about the engraving were those who were engraving post stamps, and the Swedish Post was his best choice then.

"I have never been employed," Morck says. "I like a nomadic life and I don't like bosses."

From the age of 20, Morck became a freelancer. He moved out to a small island on the Swedish west coast, sitting there engraving and drawing all day, being "quite productive and feeling quite happy".

Besides his children, only hiking and sailing can pull Morck away from work, and that is why he spends several months every year in Greenland. "When I'm working, I'm as still as a sleeping bear, so I need to be active when I am not working, just to get some balance."

He finds that balance between being active in nature and being still at work very important. "I love ice and mountains because to me they are always changing. When you walk in a mountain, you see a changing picture. When you get to a peak, there is a new peak to scale. It never ends. So you feel very humble," Morck says. "I have very high self-esteem, so I think it's very good to get that down by feeling humble."

Ice is also a constantly changing image for him. In Greenland, he will be sailing in the early morning to see the ice. "It's not white and it's not blue - it's millions of colors and shapes and it's always in a state of transformation; melting, freezing or cracking. You can see the light disappearing. You can see all the ice reflecting the moon and the sun - it's just a never-ending source of paintings."

Inspired by nature, Morck is never tired of engraving, painting and illustrating. He is also working on filming the natural beauty of Greenland.

"We think there is no other engraver quite as active as Morck," Pingel says. "It's very unique for him to see the importance of developing other skills while focusing on practicing his engraving."

Post Denmark has contacts of engravers worldwide but Morck is considered its first choice. "That's why we introduced him to China," Pingel says.

"After 40 years, I still wake up happy everyday, maybe tired but happy," Morck says. "Coming to China is just a new chapter for me. I never thought about it as a possibility. But here I am, for a new adventure."