Quote Investigator concludes that this comical proverb was first expressed in Danish and that its author remains unknown ↗. The first written instance now known is from 1948, in K. K. Steincke’s memoir Farvel og Tak, where it appears with no attribution. Bohr probably did repeat it: QI finds substantive evidence that he used the saying in 1962 or earlier. But the first published link between his name and the line that QI knows of dates from 1971, and English Wikiquote lists it under Disputed on Bohr’s page ↗.
“Prediction is very difficult, especially about the future” An anonymous Danish saying, first recorded in K. K. Steincke, Farvel og Tak (1948); often credited to Niels Bohr. Via Quotle.info
Can you use it?
? We couldn’t verify where this wording comes from, so there’s no rights status to give. Safe to present as an unverified or anonymous line — just don’t assert a specific author or source.
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In context
Evoking the themes of humility, time and doubt. Theme: "Prediction is very difficult, especially about the future". 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.
Minimalist
Minimalist editorial slide for the quote "Prediction is very difficult, especially about the future". Clean background, a single muted accent color, generous negative space, subtle paper or linen texture, no literal illustration — let the words carry it. Reserve clear space for a serif quote and a small credit line. No lettering in the image itself.
Provenance
The earliest documented instance
Work
Farvel og Tak: Ogsaa en Tilværelse IV (1935–1939)
Author
K. K. Steincke (1880–1963)
Published
København: Forlaget Fremad, 1948 · p. 227
Language
Danish. The English line is a rendering, and the popular Bohr wording is a later anonymous variant
Det er vanskeligt at spaa, især naar det gælder Fremtiden. “It is difficult to make predictions, especially about the future.”
Quote Investigator reports that Steincke placed this remark in a section on parliamentary howlers from the 1937–1938 parliamentary year, with no attribution. The Danish sentence and English rendering are given here as QI quotes them. Neither one names Niels Bohr.
1948 — The first written instance now known appears in Danish in K. K. Steincke’s Farvel og Tak, p. 227, with no attribution, per Quote Investigator ↗.
1956 — The earliest English version QI reports, in the Journal of the Royal Statistical Society, calls it a Danish proverb: “Alas, it is always dangerous to prophesy, particularly, as the Danish proverb says, about the future.” Garson O’Toole also discusses it on the American Dialect Society list ↗.
1961 — The word “prediction” appears in a Canadian Journal of Economics article: “Prediction,” goes an old Danish proverb, “is hazardous, especially about the future.” The line is still credited to no one, per Quote Investigator ↗.
1971 — The first published link to Niels Bohr known to QI appears in the Bulletin of the Atomic Scientists: “it is very difficult to predict — especially the future.” Stanislaw Ulam credited Bohr again in 1976. See Quote Investigator ↗.
No rights status can honestly be claimed for the popular English wording. It is an anonymous variant of a Danish saying whose author is unknown, so no identifiable work or first-publication date lies behind this exact sentence. The one documented source, Steincke’s Farvel og Tak, was published in 1948, after the US public-domain cutoff for published works, so nothing here should be treated as public domain.
Rights status is our research, not legal advice — and copyright varies by country and edition. For commercial or published use, confirm with the rightsholder. See terms.
Fact-check
Who gets the credit
This joke has been credited to a long line of famous wits. The documented record points to an anonymous Danish saying that was already in circulation by the 1930s.
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The most common attribution, especially among scientistsNiels Bohr Likely repeated it, didn’t coin it
Quote Investigator writes that Bohr died in 1962 and that the first published link between his name and the expression known to QI appeared in 1971. It also judges that there is “substantive evidence that Bohr employed the saying in 1962 or earlier.” A 2007 letter to The Economist, reproduced by Barry Popik ↗, says Bohr himself usually credited the saying to Storm P.
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Danish cartoonist and writer, 1882–1949Robert Storm Petersen (Storm P.) Credited, not the origin
QI cites a Danish attribution to Storm P. in LO-Bladet, dated about 1952, but notes that the date is approximate. On the ADS-L list ↗, O’Toole quotes the Oxford Dictionary of Scientific Quotations, which says Bohr attributed the line to Petersen but that it did not originate with him.
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Hollywood producerSamuel Goldwyn Very weak evidence
QI reports that the first link to Goldwyn came in The Economist in 1979. It finds the evidence that he used the saying very weak. See Quote Investigator ↗.
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Usually as “I never make predictions, especially about the future”Yogi Berra Late attribution
The earliest Berra link QI documents is a 1991 Richmond Times-Dispatch article, decades after the Danish versions. See Quote Investigator ↗.
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“It is difficult to make predictions, particularly about the future”Mark Twain Late attribution
QI first finds Twain’s name attached in a 1998 book, long after his death, with no supporting source. See Quote Investigator ↗.
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Danish poetPiet Hein Also credited
English Wikiquote notes that the line is also credited to Piet Hein, with the Danish form “det er svært at spå – især om fremtiden.” QI’s chronology does not support Hein as the originator. See Wikiquote ↗.
✓The documented origin is an anonymous Danish quip, first recorded in print in K. K. Steincke’s 1948 memoir. Niels Bohr may well have repeated it, but he did not coin it. See Quote Investigator ↗.
Context
Why Bohr’s name stuck
The line fits Bohr’s reputation. He was a Danish physicist known for paradox and dry wit, so it is easy to believe he said it. He probably did use it: Quote Investigator notes that Stanislaw Ulam, a fellow scientist who knew Bohr, credited him with it in 1976. But the joke was already in print in Denmark in 1948 with no author named. English writers were calling it a Danish proverb by 1956. Bohr’s name was attached only later.
The exact wording with “Prediction is very difficult” is itself a late variant. Earlier versions say “dangerous to prophesy,” “hazardous,” or “very difficult to predict.” The phrasing kept changing as the joke moved from one famous name to another.
Already in print in Denmark in 1948, with no author named.
Where the exact “very difficult” wording appears
Barry Popik records a social-studies textbook by Arthur K. Ellis that credits Bohr with exactly “Prediction is very difficult, especially about the future.” Popik dates the book to 1977 and says the 1970 date in Google Books is incorrect. Wikiquote cites the same book as 1970. See Barry Popik ↗ and Wikiquote ↗. Either date is later than the Danish and earlier English versions.
Explore
Filed under
More provenance-checked quotes on the same theme, each with its reuse status.
Karl Kristian Steincke, 1880–1963 · Danish Social Democratic politician and Minister of Justice
Steincke was a Danish Social Democrat. He served as Minister of Justice and as Social Minister in Thorvald Stauning’s cabinets. The fourth volume of his memoirs, Farvel og Tak (1948), contains the earliest instance of this joke that Quote Investigator has located. Steincke recorded the line but is not its proven author. He gave it, unattributed, among the “parliamentary howlers” of the 1937–1938 parliamentary year.
For writers & researchers
Cite this
Cite this page
K. K. Steincke, Farvel og Tak: Ogsaa en Tilværelse IV (1935–1939) (København: Forlaget Fremad, 1948), 227, the first written instance now known, per “Quote Origin: It’s Difficult to Make Predictions, Especially About the Future,” Quote Investigator, 20 October 2013.
This verification page
Quotle.info. “Who really said ‘Prediction is very difficult, especially about the future’?” Last verified 3 Nov 2026. https://quotle.info/who-said/prediction-is-very-difficult-especially-about-the-future/