Changyan 昌言 "Appropriate words" is a Confucian treatise from the Later Han period 後漢 (25-220 CE) attributed to Zhongzhang Tong 仲長統 (179-220), courtesy name Gongli 公理. Zongzhang was one of the "three precious scholars of the Later Han" (Houhan sanbao 後漢三賢), the others being Wang Chong 王充 (27-97 CE), and Wang Fu 王符 (83-170 CE, see Qianfulun 潛夫論). The book is also known with the title Zhongzhangzi Changyan 仲長子昌言.
The original book was 12-juan long (according to other sources, just 10) and was divided into 34 chapters. During the Song period 宋 (960-1279), only 2 juan were left. From the beginning, the text was categorized as a Confucian treatise. It criticized the tradition of the apocryphal classics that interpreted human life as determined by Heaven, which permanently sent down omens and portents in order to provide signs of human misbehaviour or of virtuous manners. Zhongzhang Tong saw human life and their activities as the centre of the universe which could by no means be influenced by the stars or the seasons. The rise and fall of a state depend, in his eyes, on the personal government of a ruler. A wise sovereign had to exhibit benevolent rule, to adapt rules and laws to circumstances, and to use reward and punishment in an appropriate way. A ruler would thus be able to govern with well-balanced harmony.
The Changyan is only preserved in fragments scattered as quotations in many different books. The Ming-period 明 (1368-1644) scholar Ye Shaotai 葉紹泰 (fl. 1638) was the first to collect those fragments and included them in his book Zengding Han-Wei-Liuchao biejie 增訂漢魏六朝别解. Ma Guohan 馬國翰 (1794-1857), a Qing-period 清 (1644-1911) scholar, detected further fragments, which are included in the Yuhan shanfang jiyi shu 玉函山房輯佚書. 2 juan of Zhangzhong's writings are included in Yan Kejun's 嚴可均 (1762—1843) Quan Houhan wen 全後漢文. The series Congshu jicheng 叢書集成 contains fragments collected by Hu Weixin 胡維新 (jinshi degree 1559) from the Ming period which he calls Zhongzhang Tong lun 仲長統論. A collection of fragments is also included in the series Silutang leiji 四錄堂類集, published by Yan Kejun.