Lǎozǐ 老子 (traditional míng Lǐ Ěr 李耳, zì Dān 聃 or Bóyáng 伯陽), the legendary author of the Dàodé jīng 道德經 (Lǎozǐ 老子), is the tutelary figure of philosophical and religious Daoism. Traditional biography (Shǐjì 63) places him as a Zhōu 周-dynasty librarian, contemporary or senior to Confucius, who, foreseeing the decline of Zhōu, left the kingdom through the Hánguǔ Pass 函谷關, there composing the Dàodé jīng at the request of the passkeeper Yǐn Xǐ 尹喜 and passing westward into the Hú 胡 lands. In the religious tradition, Lǎozǐ is the earthly manifestation of the eternally self-manifesting Most-High Lord Lǎo (Tàishàng lǎojūn 太上老君), the supreme Daoist deity in his Dào-embodied form.
Modern scholarship, through the Mǎwángduī 馬王堆 manuscripts (1973) and the Guōdiàn 郭店 bamboo slips (1993), places the composition of the received text in the 4th century BCE of the Warring States period, though individual axiomatic segments may be older in oral circulation. The book’s division into Dàopiān 道篇 and Dépiān 德篇 (or, in the Mǎwángduī order, Dépiān first and Dàopiān second) was established by the beginning of the Hàn. The canonical arrangement into 81 chapters is probably a Later-Hàn (25–220 CE) editorial intervention aligned with the He-Shang Gōng 河上公 commentary; the Mǎwángduī witnesses suggest prior arrangements of 55 or 72 sections, not 81.
For the historicity and biography see Kristofer Schipper’s entry on the Dàodé zhēnjīng in The Taoist Canon (2004, 1:58–59), Anna Seidel’s La divinisation de Lao tseu dans le Taoïsme des Han (Paris: EFEO, 1969), and A. C. Graham, “The Origins of the Legend of Lao Tan,” in Studies in Chinese Philosophy and Philosophical Literature (Albany: SUNY, 1990), 111–24.
Traditional birthdate of c. 604 BCE is a religious-biographical convention with no historical status; the frontmatter’s birthDate field preserves it as a tradition-marker without deathDate. For works in the Kanripo corpus attributed to Lǎozǐ, see KR5c0045 (Dàodé zhēn jīng — the scripture itself), and many TángSòngYuánMíng Daoist revelation-scriptures attributed to Tàishàng lǎojūn (DZ 661 KR5c0042, DZ 662 KR5c0043, DZ 657 KR5c0038, DZ 658 KR5c0039, DZ 659 KR5c0040, etc.).
For excavated recensions of the Lǎozǐ in the Kanripo corpus: KR5c0387 (Mǎwángduī Text A, before 195 BCE); KR5c0390 (Mǎwángduī Text B, 194–180 BCE); KR5c0392 (Guōdiàn bamboo slip Bundle A, ca. 300 BCE). See also KR5c0388 (the Wǔxíng 五行 found after Text A) and KR5c0389 (the Huángdì sìjīng 黃帝四經 found before Text B).