1943 onward · The record since
Tesla quote checker
Paste a line attributed to him and see which document is behind it — or that no document has been found, which is the honest answer more often than not.
What the five verdicts mean.
A quotation is a claim about a document — that on some date a particular person produced these words, and that a record of it survives. So each line below gets one of five answers, and each answer is about the state of the record rather than about how likely the sentence sounds.
- Said. A document exists, and this page names its issue and page and links to a scan or a full text.
- Altered. He wrote or said something close to this, and the version in circulation is not it. The published wording is printed beside the circulating one so the difference is visible.
- Misattributed. The words are real and belong to somebody else, who is named.
- Not said. Positively ruled out rather than merely not found: the text dates itself to a time that will not work, or the source everyone cites for it does not contain it.
- Unverified. No document has been examined here, in either direction. That covers two different situations and each entry says which it is: either nobody circulating the line has ever named a source, or a publication and date are named but the page itself has not been opened. It is the one verdict most often reported elsewhere as though it meant “fake”. It does not.
The difference between not said and unverified is the whole method. Proving a negative about a man who gave hundreds of interviews over sixty years is not generally possible. What is possible is to search the corpora that would contain it, say which ones were searched, and report the result either way.
How a verdict here is reached.
Every said verdict on this page was checked against a text, not against another quotation page. The texts used are free and open, and the links beside each entry go to them:
- My Inventions, serialised in The Electrical Experimenter in 1919.
- The Inventions, Researches and Writings of Nikola Tesla, edited by Thomas Commerford Martin, 1894 — the collected lectures and papers to that date, about a million characters.
- The periodical writing, with scans beside the transcriptions, at the Tesla Universe article collection and tfcbooks.com.
- Chronicling America at the Library of Congress, for the contemporary newspaper record.
- The United States patents, which contain no aphorisms of any kind — a patent is a legal instrument with a fixed shape, so “it is in his patents” fails before a search begins.
Where a line could not be found, the entry says which corpus was searched and what came back, including the zero results. A search that returns nothing is a result, and it is the one almost nobody publishes. The full method, with the traps — phrase searches broken by a line ending, bound volumes catalogued under the wrong year, quotation sites citing each other — is in the article this page grew out of.
What this page is not.
It is not complete, and no list of this kind can be. A line that comes back as not in this list has not been judged; it has only not been looked at here. The useful move in that case is to run the checks yourself, which takes about ten minutes against corpora that cost nothing to search.
The list
Said — 28
A document exists. Issue, page, and a link to it.
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SAID
“When wireless is perfectly applied the whole earth will be converted into a huge brain… and the instruments through which we shall be able to do this will be amazingly simple compared with our present telephone. A man will be able to carry one in his vest pocket.”
As published: “When wireless is perfectly applied the whole earth will be converted into a huge brain, which in fact it is, all things being particles of a real and rhythmic whole. We shall be able to communicate with one another instantly, irrespective of distance. Not only this, but through television and telephony we shall see and hear one another as perfectly as though we were face to face, despite intervening distances of thousands of miles; and the instruments through which we shall be able to do this will be amazingly simple compared with our present telephone. A man will be able to carry one in his vest pocket.”
“When Woman Is Boss”, as told to John B. Kennedy. Collier's, 30 January 1926, page 17
Checked against the transcription of the issue, which has it. The passage is usually assumed to be a modern invention because it describes a mobile telephone; it is a century old, and it was reprinted six weeks later on the front page of the Springfield Weekly Republican of 11 March 1926, which is in a public archive. Note that the syndicated reprint is the same interview printed twice, not independent corroboration.
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SAID
“A cheap and simple device, which might be carried in one's pocket, may then be set up somewhere on sea or land, and it will record the world's news.”
As published: “A cheap and simple device, which might be carried in one's pocket, may then be set up somewhere on sea or land, and it will record the world's news or such special messages as may be intended for it.”
“The Transmission of Electrical Energy Without Wires”, Electrical World and Engineer, 5 March 1904
The older half of the vest-pocket idea, and the reason that one is credible: a real line usually has a history as well as a citation. He had put the thought in print twenty-two years before he repeated it to Collier's.
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SAID
“The entire earth will be converted into a huge brain, as it were, capable of response in every one of its parts.”
“The Transmission of Electrical Energy Without Wires”, Electrical World and Engineer, 5 March 1904
Checked against the transcription, which has it verbatim. This is the 1904 wording. The 1926 interview says something different — “a huge brain, which in fact it is, all things being particles of a real and rhythmic whole” — and the version that circulates today is usually a blend of the two.
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SAID
“Of all the frictional resistances, the one that most retards human movement is ignorance.”
As published: “There can be no doubt that, of all the frictional resistances, the one that most retards human movement is ignorance.”
“The Problem of Increasing Human Energy”, The Century Magazine, vol. 60, no. 2, June 1900, page 211
Checked against the text of the article, which has it. The sentence immediately after it attributes a second line to somebody else — see the Buddha entry below, which is the one people get wrong.
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SAID
“Our virtues and our failings are inseparable, like force and matter. When they separate, man is no more.”
“The Problem of Increasing Human Energy”, The Century Magazine, June 1900
Checked against the text, which has it verbatim, in a passage arguing that mind and body cannot be separated in judging a man.
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SAID
“In a crystal we have the clear evidence of the existence of a formative life-principle, and though we cannot understand the life of a crystal, it is none the less a living being.”
“The Problem of Increasing Human Energy”, The Century Magazine, vol. 60, no. 2, June 1900, page 180
Checked against the text, which has it verbatim. It is quoted today as mysticism; in the article it sits inside an argument that organisms draw energy from the surrounding medium.
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SAID
“Throughout space there is energy. … it is a mere question of time when men will succeed in attaching their machinery to the very wheelwork of nature.”
As published: “Throughout space there is energy. Is this energy static or kinetic? If static our hopes are in vain; if kinetic—and this we know it is, for certain—then it is a mere question of time when men will succeed in attaching their machinery to the very wheelwork of nature.”
Checked in the full text of the 1894 collection, which has it. It is the single most quoted line in the free-energy literature, and in context it is an argument that the energy of the environment is kinetic and therefore in principle tappable — not a claim to have tapped it. The question mark after “kinetic” is usually printed as an exclamation mark, which changes a question into an assertion.
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SAID
“Ere long intelligence—transmitted without wires—will throb through the earth like a pulse through a living organism.”
Checked in the full text of the 1894 collection, which has it. It is widely reprinted with a citation to Electrical Engineer of 24 June 1892; that periodical issue was not examined here, and the 1894 volume is the copy this verdict rests on.
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SAID
“This planet, with all its appalling immensity, is to electric currents virtually no more than a small metal ball.”
“The Transmission of Electrical Energy Without Wires”, Electrical World and Engineer, 5 March 1904
Checked against the transcription, which has it. This is the premise the whole Wardenclyffe scheme rested on, stated as plainly as he ever stated it, and it is the premise that did not hold.
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SAID
“The scientific man does not aim at an immediate result. He does not expect that his advanced ideas will be readily taken up. His work is like that of the planter — for the future. His duty is to lay the foundation for those who are to come, and point the way. He lives and labors and hopes.”
Almost always dated 1934. It is 1900. Checked in both texts: the 1934 article introduces the passage with “Today I repeat again what I said to contemporary scientists of those earlier pioneering days”, and the words are already in the Century article of thirty-four years before. The 1934 citation is not wrong so much as late.
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SAID
“Today's scientists have substituted mathematics for experiments, and they wander off through equation after equation, and eventually build a structure which has no relation to reality.”
“Radio Power Will Revolutionize the World”, Modern Mechanics and Inventions, July 1934
Checked against the transcription, which has it, set as a pull-quote in the magazine. It is generally deployed today as a verdict on modern physics; in the article it is part of a specific objection to relativity, which he rejected and which held.
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SAID
“The scientists of today think deeply instead of clearly. One must be sane to think clearly, but one can think deeply and be quite insane.”
“Radio Power Will Revolutionize the World”, Modern Mechanics and Inventions, July 1934
Checked against the transcription, which has it, immediately after a sentence praising “the scientists from Franklin to Morse” as clear thinkers. It is older than the usual citation: the two sentences also appear, in reversed order and credited to “Nikola Tesla, veteran inventor”, in the Brownsville Herald of 26 July 1933, page 2 — a year before the article everyone cites.
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SAID
“Be alone, that is the secret of invention; be alone, that is when ideas are born.”
As published: “The mind is sharper and keener in seclusion and uninterrupted solitude. No big laboratory is needed in which to think. Originality thrives in seclusion free of outside influences beating upon us to cripple the creative mind. Be alone, that is the secret of invention; be alone, that is when ideas are born.”
Checked against the transcription, which has it. The line is cited variously as “An Inventor's Seasoned Ideas” and under the headline above; they are the same piece, the first being the subhead.
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SAID
“Certainly no one who is not a desirable parent should be permitted to produce progeny. A century from now it will no more occur to a normal person to mate with a person eugenically unfit than to marry a habitual criminal.”
“A Machine to End War”, as told to George Sylvester Viereck. Liberty, 9 February 1935, pages 5–7
Checked against the transcription, which has it. The passage is the one readers most often hope is a forgery, and it is not. Note the date: this article is cited across the internet, including by the companion site to a well-known documentary, as Liberty, February 1937. The editor's note introducing it calls him “now in his seventy-eighth year”, which fits February 1935 and not February 1937.
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SAID
“All repeated acts or operations I performed had to be divisible by three and if I mist I felt impelled to do it all over again, even if it took hours.”
My Inventions, chapter I, “My Early Life”. The Electrical Experimenter, February 1919
Checked in the full text, which has it. “Mist” for “missed” is not a typing error here: the magazine printed the series in a simplified orthography, and a transcription that keeps it was copied from the original rather than from a quotation site. This is the documented fact underneath the 3, 6 and 9 story, and it is a long way short of it.
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SAID
“Ere many generations pass, our machinery will be driven by a power obtainable at any point of the universe.”
The sentence the free-energy literature is built on, and it is genuine — checked in the full text. Read the two sentences on either side of it, which almost never travel with it. Before: “But such schemes are mentioned merely as possibilities. We shall have no need to transmit power in this way. We shall have no need to transmit power at all.” After: “This idea is not novel. Men have been led to it long ago by instinct or reason… We find it in the delightful myth of Antheus, who derives power from the earth.” He is speculating about a far future, and in the next breath he says the idea is not his.
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SAID
“Peace can only come as a natural consequence of universal enlightenment and merging of races, and we are still far from this blissful realization.”
My Inventions, The Electrical Experimenter, 1919
Checked in the full text, which has it. The sentence sits in a passage arguing against the League of Nations and for the United States staying out of “entangling alliances” — which is a long way from the inspirational poster it is usually printed on.
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SAID
“An inexpensive receiver, not bigger than a watch, will enable him to listen anywhere, on land or sea, to a speech delivered or music played in some other place, however distant.”
My Inventions, The Electrical Experimenter, 1919
Checked in the full text, which has it with the word “receiver”. A near-identical sentence with “instrument” instead is widely cited to “The Future of the Wireless Art”, 1908; that printing was not examined here, so if you want the wording with “instrument” it is not the one this entry verifies. Chronicling America returns nothing for either phrasing, which is expected for a passage from a monthly magazine.
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SAID
“A single ray of light from a distant star falling upon the eye of a tyrant in bygone times may have altered the course of his life, may have changed the destiny of nations.”
“On Light and Other High Frequency Phenomena”, lecture of 1893. Collected in the 1894 Martin volume
Checked in the full text. The passage ends with the line that usually travels alone: “the energy of a single thought may determine the motion of a Universe”. Note the argument it closes — conservation of energy — rather than the mysticism it is normally used for.
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SAID
“Alternate currents, especially of high frequencies, pass with astonishing freedom through even slightly rarefied gases.”
Checked in the full text. This is the observation the whole earth-and-upper-air transmission scheme rests on, stated eight years before the patents. It is also the premise that did not hold: the atmosphere does not become usefully conducting at any height a mast can reach.
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SAID
“The idea of atomic energy is illusionary but it has taken a powerful hold on the mind and there are still some who believe it to be realizable.”
“Radio Power Will Revolutionize the World”, Modern Mechanics and Inventions, July 1934
Checked against the transcription, which has it. A longer wording circulates — “so powerful a hold on the minds, that although I have preached against it for twenty-five years” — cited to The New York Times of 5 July 1931; that printing was not examined here. He was wrong, and eleven years later the point was settled by other means.
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SAID
“Of all things, I liked books best.”
As published: “Of all things I liked books the best.”
My Inventions, chapter I, “My Early Life”. The Electrical Experimenter, 1919
Checked in the full text. The circulating version drops a “the” and adds a comma, which is not worth a separate verdict, but the context is worth having: the sentence before it is “there came a tremendous change which altered the course of my whole existence”, and the one after is about his father hiding the candles so he could not read at night.
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SAID
“The last 29 days of the month are the hardest.”
As published: “The last twenty-nine days of the month are the toughest!”
My Inventions, The Electrical Experimenter, 1919
Both Wikiquote and the Tesla Universe archive list this as unverified, and both are wrong. It is in the autobiography, in the Paris chapter, spelled out and with “toughest” rather than “hardest”: asked how he was getting on, he “described the situation accurately in the statement that ‘the last twenty-nine days of the month are the toughest!’” It is a joke about being paid monthly and broke by the fourth of the month, not an aphorism. Note why the searches failed: the numeral “29” does not appear in the text at all.
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SAID
“The individual is ephemeral, races and nations come and pass away, but man remains.”
“The Problem of Increasing Human Energy”, The Century Magazine, June 1900
Checked against the text, which has it verbatim. It closes an argument that humanity behaves as one mass and not as a sum of individuals.
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SAID
“In the twenty-first century, the robot will take the place which slave labor occupied in ancient civilization.”
“A Machine to End War”, as told to George Sylvester Viereck. Liberty, 9 February 1935, pages 5–7
Checked against the transcription, which has it. Note the date again: this article is the one cited everywhere as February 1937, and it is 9 February 1935. The sentence before it is “I actually constructed ‘robots’”, which is a fair description of the 1898 wireless boat.
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SAID
“It will be more glorious to fight against ignorance than to die on the field of battle.”
As published: “Today the most civilized countries of the world spend a maximum of their income on war and a minimum on education. The twenty-first century will reverse this order. It will be more glorious to fight against ignorance than to die on the field of battle.”
“A Machine to End War”, Liberty, 9 February 1935, pages 5–7
Checked against the transcription. It comes from the same article as the particle-beam passages and the eugenics passage, which is worth knowing before quoting any of it approvingly.
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SAID
“All that was great in the past was ridiculed, condemned, combated, suppressed — only to emerge all the more powerfully, all the more triumphantly from the struggle.”
Checked against the transcription, which closes with it. One trap: at least one archive fuses this sentence with “Let the future tell the truth…”, which is a different line with a different and much weaker provenance — see that entry. If you have them as one quotation, you have two quotations.
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SAID
“I do not think there is any thrill that can go through the human heart like that felt by the inventor as he sees some creation of the brain unfolding to success.”
Wikiquote has carried this on its unsourced holding list since 18 February 2009, because the citation everyone gives — the Atlanta Constitution of 7 June 1896 — is behind a paywall. It did not need to be. The same syndicated interview ran in the Evening Star of Washington on 6 June 1896, the day before, and that page is free. The sentence was read here in the optical character recognition of the scan itself, scanner errors and all: “thrill that can go through the human heart like that felt by tho in-ventor as he sees some creation of his brain unfolding to success”.
Altered — 4
He wrote or said something close to this. The wording that circulates is not his.
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ALTERED
“The entire earth will be converted into a huge brain, which in fact it is, capable of response in every one of its parts.”
As published: “1904: “Thus the entire earth will be converted into a huge brain, as it were, capable of response in every one of its parts.” — 1926: “the whole earth will be converted into a huge brain, which in fact it is, all things being particles of a real and rhythmic whole.””
Both halves are genuine and they are twenty-two years apart. The circulating sentence welds the opening of one to the ending of the other, which produces a line he never wrote. Nothing dishonest was intended by whoever first did it, and it is still a quotation of a document that does not exist.
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ALTERED
“Peace can only come as a natural consequence of universal enlightenment.”
As published: “Peace can only come as a natural consequence of universal enlightenment and merging of races, and we are still far from this blissful realization.”
My Inventions, 1919 — the full sentence is the entry above
The circulating version stops at “enlightenment”. The sentence does not. Cutting it there removes a clause about race that most people reproducing it would not knowingly endorse, and removes the pessimism of the clause after it. A truncation is a change of meaning even when every word kept is his.
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ALTERED
“Invention is the most important product of man's creative brain. The ultimate purpose is the complete mastery of mind over the material world, the harnessing of human nature to human needs.”
As published: “The progressive development of man is vitally dependent on invention. It is the most important product of his creative brain. Its ultimate purpose is the complete mastery of mind over the material world, the harnessing of the forces of nature to human needs.”
My Inventions, chapter I. The Electrical Experimenter, 1919
The opening of the autobiography, compressed and then corrupted. Two things drift. The circulating version welds two sentences into one, and — the part that actually matters — it turns “the harnessing of the forces of nature” into “the harnessing of human nature”, which reverses what the sentence is about. Checked in the full text.
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ALTERED
“We are all one. Only egos, beliefs, and fears separate us.”
As published: “The Buddhist expresses it in one way, the Christian in another, but both say the same: We are all one.”
The first three words are his — The Century Magazine, June 1900. The rest is not
Half of this is real, which is why it survives. “We are all one” is in the June 1900 Century essay, where he is reporting what religions say rather than issuing a slogan. The second sentence — “Only egos, beliefs, and fears separate us” — is not in that essay, not in My Inventions and not in the 1894 collection, and the earliest home traced for it is a modern quotation compilation.
Misattributed — 1
Real words, and somebody else’s.
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MISATTRIBUTED
“Ignorance is the greatest evil in the world.”
Said by Tesla, but quoting the Buddha, and he says so. The Century Magazine, June 1900, page 211
The full passage reads: “of all the frictional resistances, the one that most retards human movement is ignorance. Not without reason said that man of wisdom, Buddha: ‘Ignorance is the greatest evil in the world.’” Tesla put the line in quotation marks and named its author. Quotation sites strip both and file it under his name — a misattribution created purely by cutting a sentence in the wrong place.
Not said — 3
Positively ruled out, not merely unlocated — the text dates itself wrong, or the source it cites does not contain it.
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NOT SAID
“Everything is the Light. In one of its rays is the fate of nations, each nation has its own ray in that great light source which we see as the Sun.”
A text that dates itself long after the date it claims
Circulated as a full-length interview given in 1899 to a journalist called John Smith, often with a magazine named Immortality. It cannot be what it says it is, and the internal dating settles it without any need to trace the author: the speaker argues at length against relativity and against curved space. Special relativity was published in 1905 and the curved-space theory not until 1915, so in 1899 there was nothing to argue with. He also describes the white pigeon that came to his window, a story from his last years in New York hotels. Researchers who have traced the text report that it derives from Tesla, or the Adaptation of an Angel, a drama by Stevan Pešić first staged in Belgrade in March 1995; that attribution rests on secondary reporting and is not relied on here. Lines lifted out of this text and circulated on their own carry the same verdict.
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NOT SAID
“The gift of mental power comes from God, Divine Being, and if we concentrate our minds on that truth, we become in tune with this great power.”
Printed in some modern editions of My Inventions — and absent from the 1919 original
The most instructive entry on this page, because the citation looks perfect. Good-faith quoters give a book title and a page number, which reads as the strongest possible evidence. But the words are not in My Inventions as Tesla published it: the 1919 serial in The Electrical Experimenter was searched here in full and contains neither “gift of mental power” nor “Divine Being”. They are an interpolation introduced by a later editor into certain reprint editions. A page number is a fact about the edition in your hand, not about the author.
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NOT SAID
“Our entire biological system, the brain, and the Earth itself, work on the same frequencies.”
Ruled out by its own vocabulary
This one needs no archive search, because it dates itself. The longer form that travels with it names alpha waves and a figure of 7.83 hertz. Human alpha rhythms were first published by Hans Berger in 1929 and the measurement vocabulary around them is later still; the 7.83 Hz figure is the Schumann resonance, described by Winfried Otto Schumann in 1952 — nine years after Tesla died. A sentence cannot cite a constant that will not be discovered for another nine years. For completeness, it is also absent from My Inventions, from the 1894 collection, and from Wikiquote in any section.
Unverified — 14
No document has been located, in either direction. That is a finding, not a verdict of forgery.
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UNVERIFIED
“If you only knew the magnificence of the 3, 6 and 9, then you would have a key to the universe.”
No document located
The most circulated sentence in his name. Searched: the full text of My Inventions and of the 1894 Martin collection — no occurrences of “magnificence” or “key to the universe” in either. Chronicling America, 23.8 million digitised newspaper pages — “if you only knew the magnificence” returns 0; “key to the universe” returns about 170 pages, none of them quoting him. It has sat on Wikiquote's unsourced holding list since 20 May 2015 without anyone producing a source. The earliest appearance has not been located here, and the datings reported elsewhere — a blog post of December 2009, quotation-site entries in 2013 — have not been confirmed against an archived capture.
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UNVERIFIED
“If you want to find the secrets of the universe, think in terms of energy, frequency and vibration.”
Wikiquote files it as disputed and gives one citation: a page titled “Comments from the Inventor of the Purple Harmony Plates”, from the website of a company selling plates said to carry a life-force energy. On it, the seller recalls “a conversation with the famous scientist, Dr. Nikola Tesla, in 1942” and gives this sentence, then says his products are the result. A private conversation, no third party, recalled about fifty years later, published as the origin story of the product it is selling. Chronicling America: “energy frequency and vibration” returns 0.
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UNVERIFIED
“My brain is only a receiver, in the Universe there is a core from which we obtain knowledge, strength and inspiration.”
Absent from the page it is cited to
It travels with the same citation as the energy-frequency-vibration line, to the purple-plates page. That page does not contain it — neither the Internet Archive's capture of 12 May 2006 nor the version live since. So the line has no source at all, including no bad one. Chronicling America: “brain is only a receiver” returns 0.
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UNVERIFIED
“The day science begins to study non-physical phenomena, it will make more progress in one decade than in all the previous centuries of its existence.”
No source has ever been named by anyone circulating it
Reproduced by the million and cited to nothing. Chronicling America: “non-physical phenomena” returns 0 across the whole digitised run. It was added to Wikiquote's unsourced holding list on 26 August 2012, with a standing request for a precise source, and has not moved since. Fourteen years of a public request, unanswered, is itself evidence of a kind.
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UNVERIFIED
“Marconi is a good fellow. Let him continue. He is using seventeen of my patents.”
No contemporary printing located
The most attractive line in the set, because it is generous and funny and fits everything else known about him. It is placed in December 1901, as a reply to an engineer who said Marconi had got the jump on him. Wikiquote files it under “Attributed” and cites a public-television web feature, which names no document. Chronicling America: “seventeen of my patents” returns 0. It may well have been said — a remark to a colleague in a laboratory has no reason to reach a newspaper — but “may have been said” and “is documented” are different states. What the patents actually covered does not depend on the anecdote: that is settled in the Supreme Court's 1943 opinion.
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UNVERIFIED
“If your hate could be turned into electricity, it would light up the whole world.”
No document located
Widely attached to his name on image macros and quotation sites, always without a citation. Chronicling America: “if your hate could be turned into electricity” returns 0. It is not in My Inventions or in the 1894 collection. No book, article, letter or interview has been named by anyone circulating it.
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UNVERIFIED
“I don't care that they stole my idea. I care that they don't have any of their own.”
No source has ever been named
One of the most shared lines in his name and one of the least sourced. Absent from the full text of My Inventions and from the 1894 collection. No book, article, letter or interview has been named by anyone circulating it. The register is wrong too: it is a modern internet sentence, short and barbed, and nothing else attributed to him from a printed source reads like it.
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UNVERIFIED
“Let the future tell the truth, and evaluate each one according to his work and accomplishments. The present is theirs; the future, for which I really worked, is mine.”
Attributed to an interview in Politika, Belgrade, April 1927, as quoted in modern biographies. That issue was not examined here
This one is probably real and it is still not verified, which is the distinction the page exists to keep. A publication and a month are named, which puts it well above the unsourced lines — but every printing traced runs through a modern book quoting the 1927 interview rather than through the interview. Chronicling America returns 0 for “let the future tell the truth”, which proves little either way: a Serbian newspaper interview has no reason to appear in digitised American newsprint. What would settle it is the Politika issue.
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UNVERIFIED
“I hold that space cannot be curved, for the simple reason that it can have no properties.”
Attributed to the New York Herald Tribune, 11 September 1932. That page was not examined here
A publication and an exact date are named, which is more than most lines have, and it fits a documented pattern: he rejected relativity in print repeatedly, including in The New York Times of 11 July 1935. But the citation chain runs through quotation collections rather than a scan, the Herald Tribune is in no free archive for 1932, and this page does not print a verdict of “said” on a page it has not opened.
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UNVERIFIED
“You may live to see man-made horrors beyond your comprehension.”
A recollection printed in Esquire, October 1947, page 125 — four years after his death
Better sourced than most of this group and still not documented. The line is given in a 1947 magazine profile, as something Tesla is said to have told a visitor about the 1898 wireless boat, forty-nine years earlier and four years after he died. No contemporary printing has been located. What the 1898 press actually quotes him saying about the boat is the opposite in tone — he presented it as a device that would make war impossible.
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UNVERIFIED
“No free energy device will ever be allowed to reach the market.”
No source has ever been named
An image-macro line, flagged as such on Wikiquote's talk page in 2021 and never sourced since. Absent from both full texts. Chronicling America returns four pages carrying the phrase “free energy device”, all from 1917–18 and none about Tesla. The vocabulary is the giveaway: “free energy device” as a noun phrase belongs to late-twentieth-century fringe-energy writing. His own term was the energy of the ambient medium — see the 1892 passage above, which is real.
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UNVERIFIED
“What one man calls God, another calls the laws of physics.”
No source has ever been named
High on the quotation sites and absent from every Tesla reference work searched, including Wikiquote, where it does not appear even as unsourced. Chronicling America: 0. What he is documented as saying in this register is sharper and less comfortable — in Liberty of 9 February 1935 he writes that “what we call ‘soul’ or ‘spirit’ is nothing more than the sum of the functionings of the body”.
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UNVERIFIED
“Science is but a perversion of itself unless it has as its ultimate goal the betterment of humanity.”
No source has ever been named
On Wikiquote's unsourced holding list since the very first batch was moved there on 18 February 2009, and not carried by the Tesla Universe archive at all. Seventeen years of a standing public request for a source, unanswered. The nearest documented sentiment is the 1900 Century passage on ignorance, which is in this list and does have a page.
The document
There is no single document behind this page; there is one behind each entry, and it is named there. The two standing texts every line was checked against are My Inventions, The Electrical Experimenter, February, March, April, May, June and October 1919 — full text — and Thomas Commerford Martin (ed.), The Inventions, Researches and Writings of Nikola Tesla, The Electrical Engineer, New York, 1894 — full text.