Personally Written Poetry is an album by Cai Xiang, one of four most celebrated Northern Song calligraphers. The work, which records his monthslong journey from Fuzhou in today's Fujian province to the national capital city of Bianliang (today's Kaifeng, Henan) reflects his career peak.

"It was hailed as Cai's finest work by Zhang," Hao says. "It greatly influenced Zhang's own calligraphy as well."

Also on show is the scroll, One Hundred Flowers, which is believed to have been painted by a female artist named Yang Jieyu from the Southern Song Dynasty (1127-1279), and portrays blooms, including those of lotuses, orchids and sun-flowers in 17 scenes. It is the only known painting by Yang.

Nevertheless, rules of the Palace Museum demand that a paperwork collection should stay in its warehouse for at least three years before every public exhibition. Consequently, some listed works in the catalog are replaced by replicas if they have been displayed once in recent years.

Visitors are also able to view A Consoling Letter (Pingfu Tie) by Lu Ji of the Western Jin Dynasty (265-316), the oldest extant work of model calligraphy, and Spring Excursion, an early example of Chinese landscape painting attributed to Zhan Ziqian of the Sui Dynasty (581-618), through their replicas.

"This exhibition will remind today's private collectors of their social duty," says Lou Kaizhao, Zhang's grandson, who's co-curator of the exhibition. "If my grandfather had kept his collection in an attic, the general public would have little idea about such masterpieces."