There are three books of the title Sizijing 四字經 "Four-characters classic", one written by the Tang-period 唐 (618-907) Zen monk Dexing Chanshi 德行禪師, one by the Ming-period 明 (1368-1644) scholar Xiao Liangyou 肖良友, and one by the Italian Jesuit father Giulio Aleni (1582-1649, Chinese name Ai Rulüe 艾儒略).
Dexing's 德行 Sizijing is written in four-character verses that explain natural phenomena and social relations. Quite a few of these sentences are today still known as Chinese proverbs, like zuojing guantian 坐井觀天 "to observe the sky from the bottom of a well", dianshi chengjin 點石成金 "to turn stone into gold with a touch", or shouzhu daitu 守株待兔 "to stand by a tree stump waiting for a hare (to dash itself against it)". His book was commented during the Ming period by Zhou Lüjing 周履靖 (1549-1640) and is included in the series Yimen guangdu 夷門廣牘 and Congshu jicheng chubian 叢書集成初編.
Xiao Lianyou's 肖良友 Sizijing is an imitation of the famous textbook Sanzijing 三字經, but with a focus on Chinese history. While the Sanzijing is 1,248-characters long, the Sizijing has a length of 4,400 characters.
Aleni's book is an introduction into Christian teachings written in the style of Chinese elementary textbooks for small children, like the Sanzijing. The preface was written in 1663, but the book was already printed as early as 1642, and then later by the Tushanwan Press 土山灣印書館.
The term sizijing 四字經 is also used to denote "fundamental knowledge" in professional fields.