AN INSCRIBED IMPERIAL OCTAGONAL INKSTONE MARK AND PERIOD OF QIANLONG, DATED TO 1776

the black inkstone of flat octagonal form, carved to one side with a slightly graded surface pooling the water in a small well, the reverse with a slighlty recessed based inscribed with two seals, De chong fu ('Sign of Virtue Within') and Hui xin bu yuan ('Enlightened Mind Not Far'), below a five-character title at the top, reading Tang Guanxiang ('Observing Heaven') followed by a long poem dated to the bingshen year corresponding to 1776, fitted Japanese wooden box 

Mayuyama Ryusendo, Tokyo, October 1987.
Private Japanese Collection.
Hirano Kotoken, Tokyo.

The overall condition is quite good, with the exception of a few nicks to both sides of the inkstone, including a 0.4 x 0.5 cm chip above the well.
"In response to your inquiry, we are pleased to provide you with a general report of the condition of the property described above. Since we are not professional conservators or restorers, we urge you to consult with a restorer or conservator of your choice who will be better able to provide a detailed, professional report. Prospective buyers should inspect each lot to satisfy themselves as to condition and must understand that any statement made by Sotheby's is merely a subjective, qualified opinion. Prospective buyers should also refer to any Important Notices regarding this sale, which are printed in the Sale Catalogue.
NOTWITHSTANDING THIS REPORT OR ANY DISCUSSIONS CONCERNING A LOT, ALL LOTS ARE OFFERED AND SOLD AS IS" IN ACCORDANCE WITH THE CONDITIONS OF BUSINESS PRINTED IN THE SALE CATALOGUE."

The inscription can be translated as follows:
Imitation Tang Guanxiang ('Observing Heaven') Inkstone

The ancient sage observed heaven,
And put his ideas to pen.
Although eight trigrams were drawn,
Their principles were primordial.
Who has made this inkstone
To expound on The Book of Change?
With four sides and four corners,
Neither a square nor a circle,
Further adding yin and yang,
Now all components are present.
Playful words to add on it,
Choosing a stone to imitate it.
Dripping dew to grind ink red,
It will aid me till the end of day.
Imperial inscription on the New Year's Day of the bingshen year

The present inkstone takes its form from one the ten old inkstones of particular fine quality from the Palace collection chosen by the Qianlong emperor in the 14^th year of his reign (1749) to be bestowed with a name and dating. The first of these inkstones was an octagonal Duan stone, named Guanxiang and attributed to the Tang period by the emperor.  A closely related She stone example was included in the exhibition The Imperial Studio, Littleton and Hennessey Asian Art, London, 2009, cat. no. 15, which also includes a discussion of the context of this type of inscribed octagonal inkstone. For a duan inkstone inscribed with an imperial poem and carved in the form of a Han tile see one sold in these rooms, 30^th November 1980, lot 580.