Private letters exchanged between intellectuals living centuries back manifest the best of Chinese calligraphy art and, meanwhile, provide a glimpse of the social etiquette, cultural life, and history of the time.

Well-kept letters attributed to prominent calligraphers in ancient times, with sound sources of origin, are sought-after among collectors.

One such example will go under hammer during Poly Auction's major sales this week, from Tuesday to Sunday.

The piece by Zhang Jizhi, from the Southern Song Dynasty (1127-1279), is believed to be written to an unknown friend in which he updated his life after retiring from the royal court.

Poly's upcoming auction in Beijing will offer objects of Chinese works of art, including paintings, calligraphy, ceramics, vintage books and manuscripts.