Loose paraphraseReal idea, reworded
High
Checked by the editor · 8 Oct 2026
Attributed to Confucius
Real knowledge is to know the extent of one's ignorance.
Not quite. Analects 2.17 tells you to admit what you do not know, not to measure ignorance.
Source line
知之为知之，不知为不知，是知也。
zhī zhī wéi zhī zhī, bù zhī wéi bù zhī, shì zhī yě.
Yu, 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.
Analects · 2.17 · tr. James Legge (Gutenberg #3330)
Explanation
Not quite. "Real knowledge is to know the extent of one's ignorance" is a paraphrase of the Analects, 2.17, not the sentence Confucius is given there. The Chinese is 知之为知之，不知为不知，是知也. It sits inside a direct remark to someone named Yu, and the public-domain translation keeps that address. The popular line drops Yu, drops the double instruction, and substitutes a different proverb about measuring how large your ignorance is. Nearby is not the same as identical.
James Legge's English is the text to cite. He has the teacher ask Yu whether he shall teach him what knowledge is. When you know a thing, you hold that you know it. When you do not know a thing, you allow that you do not know it. That, Legge writes, is knowledge. The original is about honesty in naming your own mind, case by case. It does not ask you to survey "the extent" of your ignorance, and it never says "real knowledge". Quote Analects 2.17, and leave Yu in the sentence.
Share it accurately
Analects 2.17, tr. Legge: when you know a thing, hold that you know it; when you do not, allow that you do not.
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Confidence: high. An exact passage is in the cited edition, or a named source documents the origin. How confidence works
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