Kǒng Jǐ 孔伋, courtesy name Zǐsī 子思, was the grandson of Confucius 孔子 (Kǒng Qiū 孔丘) and son of Kǒng Lǐ 孔鯉 (Bóyú 伯魚). He was born in the state of Lǔ 魯 and is traditionally dated ca. 483–402 BCE (conventional), though some ancient sources place his death as late as 350 BCE. He is said to have studied under Zēngzǐ 曾子 (Zēng Shēn 曾參) and to have taught Mèngzǐ’s 孟子 own teacher, forming the critical link in the transmission Confucius → Zēngzǐ → Zǐsī → Mèngzǐ that became orthodox in Song Confucianism. He served at the Wèi 衛 court and had close interactions with Duke Mù of Lǔ 魯穆公 (as preserved in KR2p0151).
Zǐsī is the putative founder of the “Zǐsī–Mèngzǐ” school (Zǐsī Mèngshì zhī rú 子思孟氏之儒), one of the eight post-Confucian Ru traditions catalogued in the Hán Fēizǐ (chapter “Xiǎn xué” 顯學). The discovery of the Guōdiàn bamboo-slip manuscripts (ca. 300 BCE, see KR2p0150, KR2p0151, KR2p0152) has reinvigorated debate about which texts belong to the Zǐsī school. Strong candidates include the Zīyī 緇衣, Lǔ Mùgōng wèn Zǐsī 魯穆公問子思, Wǔ Xíng 五行, Chéng Zhī Wén Zhī 成之聞之, and Táng Yú Zhī Dào 唐虞之道. The received Zhōngyōng 中庸 (a chapter of the Lǐjì 禮記) is traditionally attributed to him, as is the Zǐsī zǐ 子思子 — a work known only in fragments.
No confident CBDB match exists; Zǐsī predates the CBDB coverage period. CBDB does not contain an entry for 孔伋.