No dream discovery is cited more often than this one: Dmitri Mendeleev is said to have seen the entire periodic table of the elements in a dream – finished, as if someone had laid the chart before him. It is the most famous story of our little dream genre – and at the same time the most weakly supported. That is exactly why it is the right conclusion to the series around Loewi, Kekulé, Tesla and Ramanujan: it shows where the line between inspiration and legend runs.
What Mendeleev really achieved
Dmitri Ivanovich Mendeleev (1834–1907), born in Tobolsk in Siberia, was a Russian chemist of extraordinary range. In 1869 he formulated the periodic law: arrange the elements by increasing atomic weight, and their chemical properties recur periodically. His stroke of genius was not only the sorting but the courage of the gap: where the periodicity demanded an element no one knew, he left a place open and predicted its properties. When "eka-aluminium", "eka-silicon" and "eka-boron" were indeed found a few years later – as gallium, germanium and scandium, with strikingly accurate properties – the system was brilliantly confirmed. That is Mendeleev's lasting achievement, with no dream at all.
The dream legend
The story itself does not come from Mendeleev but second-hand – from the geologist and university colleague Alexander Inostrantsev (1843–1919). By his account, Mendeleev had told it to him personally; Inostrantsev later liked to share the anecdote with his students, and it was written down only in his memoirs, which appeared after Mendeleev's death (1907). According to it, the exhausted Mendeleev, after three sleepless days brooding over the arrangement of the elements, finally fell asleep and saw in a dream a table "in which all the elements fell into place exactly as required"; he woke, noted it down at once – and had to correct only a single spot later. Catchy as that sounds: it is a single account from his circle, one that Mendeleev himself never confirmed – on the contrary, he always pointed to long, hard work.
Why the legend wobbles
Here is the necessary honesty – and it is sharper than in the other cases.
- A single second-hand source. No dream report by Mendeleev exists. The scholarly literature (for instance an analysis in the journal Dreaming, 1995) rates the story as probably legendary – often cited, never substantiated.
- The drafts tell a different story. Mendeleev's surviving worksheets of 17 February 1869 (Russian calendar) show a laborious, step-by-step back-and-forth – he pushed cards bearing element names around like a game of solitaire ("chemical solitaire"). The archival researcher B. Kedrov concluded that the table largely stood before the alleged dream; a dream may later have shown an improved arrangement, but it did not create it out of nothing.
- From Mendeleev himself there is no reliable testimony on this. He nowhere recorded the dream in his own hand – but neither is there a denial in his own hand. The remark often cited against it – that he had thought about the problem for years, and then people suppose one sits down and suddenly it is all finished – is itself only attributed (the number of years varies from telling to telling) and thus rests on the same anecdotal ground as the dream story. Some historians even suspect that Mendeleev, in old age, rather cultivated such legends. What is reliable, therefore, is not what he is said to have stated, but what he left behind: his working drafts.
A cautious reading, then, runs: the table grew out of sustained thinking; if a dream played any part at all, perhaps an accompanying or clarifying one rather than a solely creative one (so the archival researcher Kedrov). The romantic version – the finished chart as a mere gift of sleep – is not supported by the sources; but neither can it be entirely ruled out. What is certain above all is the long, patient work behind it.
The ether at position zero
A detail that surprises many and shows nicely that this system, too, was no finished form fallen from the sky: around 1902–1904 Mendeleev tried to incorporate the then still-believed luminiferous ether as a chemical element into his table. He conceived it as an extremely light, chemically inert gas – lighter than hydrogen – and named it "Newtonium" (together with a hypothetical "coronium"). Inspired by the freshly discovered noble gases (the "group zero"), he placed the ether in a group zero, period zero: right at the top, before hydrogen – that is, at the zero position at the head of the system.
With the end of the ether concept – the Michelson–Morley experiment and Einstein's special theory of relativity (1905) – this entry vanished again. So the popular image "the ether stood at the top and was later removed" hits the mark: it was not a displacement of hydrogen but a separate zero position above it – but yes, the ether stood at the head of the table and was struck out.
A sceptic, of all people
A side note that fits the sobriety of this case: Mendeleev was visibly sceptical of the spiritualism then in vogue – and that of his own initiative. In 1875 he himself proposed a commission of the Russian Physical Society (so it was no duty assigned to him), which at St Petersburg University examined spiritualist mediums. An explicit self-declaration as an "opponent" is not readily found in his writings – but his conduct speaks plainly enough. In its 1876 conclusion it held that the phenomena rested on unconscious movements or conscious deception and that the spiritualist doctrine was "superstition". That blanket sentence – from the few mediums tested to spiritualism as a whole – is, however, the commission's pointed closing formula, not necessarily Mendeleev's own line of argument. His own concern, as his biographer Michael Gordin shows, was less to prove that every medium cheats than to draw a boundary: that science, not the séance, should rule on natural phenomena, and that extraordinary claims must be provable under controlled conditions. What he rejected was the unproven claim – that is burden-of-proof reasoning, not an inference from a small sample to all. The blanket generalisation itself was contested by the spiritualists around Alexander Aksakov (a rebuttal in 1883). He published his arguments together with the minutes in 1876 in a book of his own, Materials for Judging Spiritualism (also told at length by his biographer Michael Gordin). The man with whom posterity associated the most famous dream story thus dealt with supernatural claims in a markedly testing spirit – a further indication that the dreamt-up finished chart fits him poorly.
What remains – and what the case teaches
With this our dream arc closes on a salutary contrast. For Otto Loewi the dream supplied a testable experiment that passed the test – the strong case. For Mendeleev the dream is, by contrast, mainly a second-hand later narrative laid over years of methodical work, one for which no first-hand testimony exists – the weak case. Both belong together because they show the same boundary from two sides.
The lesson is not "dreams don't matter", but: a catchy flash-of-genius story is not yet proof that the insight arose that way. Creative work is mostly long, patient preparation – out of which an idea (sometimes in half-sleep) draws the missing form, which must then be tested while awake. It is precisely this distinction – open to the inspiration, strict in the evidence – that runs through all five portraits and through this whole site. More on the underlying question in our piece on the assumption that the brain produces consciousness.
Sources:
• Michael D. Gordin, A Well-Ordered Thing. Dmitrii Mendeleev and the Shadow of the Periodic Table, Revised Edition, Princeton University Press, Princeton 2019 (ISBN 978-0-691-17238-5) – the definitive biography, including the ether episode and Mendeleev's critique of spiritualism.
• What Do We Really Know About Mendeleev's Dream of the Periodic Table? A Note on Dreams of Scientific Problem Solving, in: Dreaming 5(4), 1995 (doi) – the critical examination of the dream anecdote.
• D. Mendeleev, On the Relationship of the Properties of the Elements to their Atomic Weights, Journal of the Russian Chemical Society, 1869 – the first publication of the periodic law.
• D. Mendeleev, Materials for Judging Spiritualism (Russian "Materialy dlya suzhdeniya o spiritizme"), St Petersburg 1876 – Mendeleev's own work against spiritualism.
Continue in our curated knowledge collection – see the sister articles on Otto Loewi's dream experiment, on Kekulé's benzene ring dream, on Nikola Tesla's visions and on Ramanujan and the goddess Namagiri, as well as on the question of brain and consciousness.