The present lot belongs to a group of seals dating to the twilight period of Emperor Qianlong's life, shortly before his retirement in favour of his fifteenth son, Rongyan, who ascended the throne as the Emperor Jiaqing. One of a series of Qianlong's personal seals, it is clearly evident from the seal characters, Bajing Maonian, that the present seal was commissioned to commemorate Qianlong's eightieth birthday in 1791. A seal impression almost identical to the present seal chop is published in Zhongguo Shuhuajia Kuanshi, Shanghai Museum publication, 1987, p.248, no. 159 (see fig. 1).
Compare to two very similar seal chops, both carved in positive text, in the Palace Museum, Beijing. The first of these is a large white jade 'double dragon' seal included in the exhibition, Qing Legacies: The Sumptuous Art of Imperial Packaging, Macau Museum of Art, 2000, illustrated in the Catalogue, p. 87, no. 18; where it is illustrated together with a seal commemorating Qianlong's seventieth birthday, ibid. The other is of spinach-green jade illustrated by Guo Fuxiang, Ming Qing Dihou Xiyin, Beijing, 2002, p. 153.
During the latter period of the Qianlong reign, the Emperor prided himself of his long life and achievements. As such, a variety of seals were carved with characters that reflected these sentiments, for example a spinach-green jade seal carved with four characters, Xinyuan Fuchu, '(My) Expectations Accomplished', illustrated by Guo Fuxiang, op. cit., 2002, p. 164; a spinach-green jade seal bearing the seal chop, Xiquan laoren zhibao, 'A treasure of the perfect elderly gentleman', illustrated in The Life of Emperor Qianlong, Macau Museum of Art, 2002, no. 6; and a large jade seal with the characters, Wufu wudai tangbao, 'Five generations of off-springs in one's lifetime', illustrated in Ming Qing Dihuo Baoxi, Forbidden City Press, 1996, p. 153. All these cited seals contrast greatly to those of Qianlong's youth, such as a set of three 'princely' seals that once belonged to Qianlong whilst still a prince, sold in these Rooms, 3 November 1998, lot 1077, and sold again at Sotheby's Hong Kong, 26 October 2003, lot 26. One of these three seals reverberates youth and expectations as reflected in its seal chop, Changchun jushi, 'The dweller in everlasting Spring'.
Compare also personal seals that were produced after Qianlong's abdication, inscribed with the characters Taishang huangdi zhibao, 'Treasure of the Emperor Emeritus'. After his abdication, Qianlong styled himself Taishang Huangdi, Emperor Emeritus, following the ancient tradition as recorded in the Shiji, 'Records of the Grand Historian', written by Sima Qian (c. 145-86 BC). For two examples from the Palace Museum, Beijing, see, op. cit., Macau Museum of Art, 2002, no. 7, for a white jade seal; and a spinach-green jade seal, illustrated by Guo Fuxiang, op. cit., 2002, p. 161.