The Storm Is Coming, oil on canvas by Zhong Han.

At age 84, Zhong Han describes himself as an "immature elderly painter", and that he is only "a tree in the forest that keeps absorbing nutrition from the earth".

Zhong's modesty and persistence in chasing perfection explain why he has just held a solo exhibition, celebrating his six-decade love of oil painting.

A professor with the Central Academy of Fine Arts, Zhong is displaying nearly 300 works at his retrospective, titled Earth and Humanity, at the National Art Museum of China.

A highlight of the exhibition is the juxtaposition of two large paintings with the same title, Along the Yanhe River.

Zhong painted the original in 1963, in which he portrayed Mao Zedong walking with a farmer along the river in Yan'an, the "cradle of China's communist revolution" in Shaanxi province.

A golden rule at that time was to show the late leader's brilliance by painting him front on or his side profile. Zhong made a brave breakthrough by painting Mao's back.

"The innovative approach displays a confident and resolute leader, as well as his earnest, unpretentious and approachable side," comments Fan Di'an, director of the National Art Museum of China.

The painting was highly acclaimed and widely covered by media. But it was unfairly treated during the "cultural revolution" (1966-76), when the Red Guards violently stamped on it.

Zhong thought the painting was totally destroyed, and he recreated a smaller version in 1999.