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Who really said it

When you know a thing, to hold that you know it; and when you do not know a thing, to allow that you do not know it — this is knowledge

Written by (translated) Confucius 551–479 BC · Chinese philosopher & teacher
Verified Free to reuse

This is a genuine, well-known saying of Confucius — Analects, Book II, Chapter XVII — in the classic English translation by James Legge (1861). The Chinese original 知之為知之，不知為不知，是知也 is spoken by Confucius to his disciple Zhong You (Zi Lu), and Legge’s wording matches word for word.

Last verified 10 Jul 2026 · how we verify · spot an error?

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“When you know a thing, to hold that you know it; and when you do not know a thing, to allow that you do not know it — this is knowledge” Confucius, The Analects, Book II, Ch. 17, trans. James Legge (1861)

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In context

Evoking the world of Confucius — Chinese philosopher, teacher & editor of the classics. Theme: "When you know a thing, to hold that you know it; and when you do not know a thing, to allow that you do not know it — this is knowledge". Atmospheric and restrained, cinematic directional light, a muted period-appropriate palette, fine grain and texture. Compose with generous empty space for the quote and a small credit line. No lettering in the image itself.

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Provenance

The source

Work
The Confucian Analects (Lunyu 論語), Book II, Chapter XVII
Spoken by
Confucius (551–479 BC), to his disciple Zhong You (Zi Lu)
Translation
James Legge, 1861 (revised 1893)
Original
知之為知之，不知為不知，是知也

The Master said, ‘You, shall I teach you what knowledge is? When you know a thing, to hold that you know it; and when you do not know a thing, to allow that you do not know it — this is knowledge.’

Legge’s English, set beside the Chinese original 子曰：「由！誨女知之乎？知之為知之，不知為不知，是知也。」 at the Chinese Text Project.

Analects 2.17 (Wei Zheng) — Chinese original with Legge's translation, Chinese Text Project

How we traced it

  • The wording is James Legge’s, first printed in The Chinese Classics, Vol. 1 (1861), Confucian Analects, Book II, Ch. XVII, verse 9, as documented by Today in Science.
  • The Chinese Text Project ↗ shows the same passage (Wei Zheng 17) with Legge’s translation beside the original Chinese, confirming both the source and the translator.
  • Wikiquote ↗ lists the original 知之為知之，不知為不知，是知也 under the Analects, Book II, confirming the passage is authentic to Confucius.
Public domain

The original Chinese Analects is ancient and long in the public domain. The exact English wording here is James Legge’s translation, first published in The Chinese Classics, Vol. 1 (Hong Kong, 1861) and revised in 1893 — both editions are well before 1931, so this translation is in the public domain in the United States.

This reflects the original work, which is public domain. If your exact English wording comes from a specific modern translation, that translation may itself still be under copyright — check the edition you quote.

Fact-check

A real quote — but watch the paraphrases

This exact line is genuine Confucius. But Confucius is one of the internet’s biggest fake-quote magnets, and this teaching in particular circulates in loosened, translator-free paraphrases that people pass off as his literal words.

“Real knowledge is to know the extent of one’s ignorance.” paraphrase

Widely shared as a direct Confucius quote, this is a loose modern rendering of the same passage (Analects 2.17), not a literal translation of the Chinese — it circulates with no translator or edition attached, as seen across sites like BrainyQuote ↗.

“To know what you know and what you do not know, that is true knowledge.” variant wording

A shortened restatement of Legge’s line that spreads without noting it is a paraphrase; the documented wording spoken to Zhong You is Legge’s fuller sentence quoted above.

The thought — and this specific wording — genuinely trace to Confucius via Analects 2.17 in James Legge’s 1861 translation; only the trimmed meme versions are unmoored paraphrases.

Context

Why it endured

The saying compresses a whole theory of learning into one sentence: knowledge is not just what you have grasped, but the honesty to mark off what you have not. Confucius addresses it to his headstrong disciple Zhong You (Zi Lu), a warning against bluffing.

It has become a touchstone for intellectual humility, quoted alongside Socrates’ ‘I know that I know nothing’ as an ancient East-meets-West statement that admitting ignorance is itself a form of wisdom.

To own what you know, and own what you don’t — that is knowledge.

Explore

Filed under

More provenance-checked quotes on the same theme, each with its reuse status.

Knowledge Wisdom Truth

Go further

Dig deeper

Trusted places to keep pulling the thread — primary archives, fact-checks, and scholarship. We show how we used each one before you leave.

Analects 2.17 — Chinese + Legge (Chinese Text Project)ctext.org

The authoritative side-by-side: Confucius’s original Chinese with James Legge’s English translation of the passage.
Confucius — Wikiquoteen.wikiquote.org

Lists the original Chinese of Analects 2.17 and multiple translations, confirming the saying is authentic.
Confucius quotations (with 1861 Legge citation)todayinsci.com

Gives the exact wording with a full Legge citation: The Chinese Classics (1861), Vol. 1, Book 2, Ch. 17.
The Analects — Confucius (Book II)web2.qatar.cmu.edu

A course text carrying the full-context Legge passage, ‘Yu, shall I teach you what knowledge is?’
Confucian Analects (Legge) — Internet Sacred Text Archivesacred-texts.com

Full public-domain text of Legge’s Confucian Analects, including Book II.

The true author

Confucius (Kong Qiu)

Confucius

551–479 BC · Chinese philosopher, teacher & editor of the classics

Confucius (Kong Qiu, courtesy name Zhongni) was a teacher and philosopher of the Spring and Autumn period whose sayings were gathered by later disciples into the Lunyu, or Analects. His ethics of learning, honesty, and self-cultivation shaped East Asian thought for two millennia. This line — that real knowledge means owning both what you know and what you don’t — is one of his most quoted teachings on intellectual honesty.

For writers & researchers

Cite this

Primary source — Chicago

Confucius. The Confucian Analects, in The Chinese Classics, vol. 1. Translated by James Legge. Hong Kong, 1861. Book II, ch. 17.

MLA (9th ed.)

Confucius. The Confucian Analects. Translated by James Legge, 1861.

APA (7th ed.)

Confucius. (1861). The Confucian analects (J. Legge, Trans.). (Original work composed 5th century BCE)

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Quotle.info. “Who really said ‘When you know a thing, to hold that you know it; and when you do not know a thing, to allow that you do not know it — this is knowledge’?” Last verified 10 Jul 2026. https://quotle.info/who-said/when-you-know-a-thing-to-hold-that-you-know-it-and-when-you

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