"As time goes by, good works never wither but erupt with renewed vitality, because they show an eternal beauty, an artist's true heart, sincerity and concern with others which should still be treasured today, and that is why these works are gathered for display," Yang says.

Tai Wuqi, the exhibition curator, says Chen sees the Tibetan paintings as a label he finds difficult to rip off.

Chen didn't show up at the exhibition opening on May 11, but Tai invited him to drop by days earlier. Chen wrote brief comments on the wall, below some of the works on show.

"Some comments are hidden in the shadow of the paintings, and people may not notice them at first glance. It's like a game Chen plays with people, to feel his inconspicuous presence at the exhibition," Tai says.

In one comment for Mothers and Children, one of the Tibetans series, Chen wrote, "Look at the center woman, you won't get to see the real person. (She was) very, very pretty. Girls these days can't rival her at all!"

Beside the preparatory sketches for Washing Hair, another Tibetan work, a comment reads, "Any of these drafts is better than the finished painting. What can I do with it?"

In an article to review the series in 2009, Chen said: "Things have changed. It is as if I were looking at works by someone else. They (the Tibetans series) were done with much devotion, and enormous kindness."