This statement attributed to Charles Duell has been authoritatively debunked for quite some time but still seems to cling to a life all its
own, I suppose, because the statement has a certain quality about
it that people find amusing.

Here below is an excerpt/link to what amounts to a convincing case
as only one small step towards restoring the honor of the poor, lamentably impugned otherwise qualified Commissioner, U.S.Office
of Patents, Charles H. Duell.
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A Patently False Patent Myth still! Did a patent official really once resign because he thought nothing was left to invent? Once such myths start they take on a life of their own – 1989 article reprinted – Reprint
Skeptical Inquirer, May-June, 2003 by Samuel Sass

It is rare that we feel moved to republish an earlier SKEPTICAL INQUIRER article. But the myth that a patent commissioner once resigned because “everything that can he invented has been invented” keeps being uncritically repeated in prominent news outlets. So we thought it would he interesting and useful to reprint Samuel Sass's brief article investigating that claim, “A Patently False Patent Myth,” from our Spring 1989 issue. The article has not appeared in any SI anthology. Author Sass has slightly revised one paragraph, and at the end he provides an update.

For close to a century there has periodically appeared in print the story about an official of the U.S. Patent Office who resigned his post because he believed that all possible inventions had already been invented. Some years ago, before I retired as librarian of a General Electric Company division, I was asked by a skeptical scientist to find out what there was to this recurring tale. My research proved to be easier than I had expected. I found that this matter had been investigated as a project of the D.C. Historical Records Survey under the Works Projects Administration. The investigator, Dr. Eber Jeffery published his findings in the July 1940 Journal of the Patent Office Society…..link to the article.

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