Did Dmitri Mendeleyev conjure the organization of elements into the periodic table in a dream?

Among the several places I've seen this suggested is the review of a book (that I haven't read) on Amazon called "Mendeleyev's Dream: The Quest for the Elements", which states:

On the night of February 17, 1869, the Russian scientist Dmitri Mendeleyev went to bed frustrated by a puzzle he had been playing with for years: how the atomic weights of the chemical elements could be grouped in some meaningful way--and one that, with any luck, would open a window onto the hidden structure of nature. He dreamed, as he later recalled, of "a table where all the elements fell into place as required." His intuition that when the elements were listed in order of weight, their properties repeated in regular intervals, gave rise to the Periodic Table of the Elements--which, though much revised since, underlies modern chemistry.

Was this actually a dream that occurred during sleep, as this suggests?

  • 1
    Is this answerable as asked? – horatio Jul 20 '11 at 15:40
  • 3
    This is not that improbable. Often I will work on hard problem for hours (software development) and only when I am in bed at night almost asleep will the answer come to me. – Craig Jul 21 '11 at 3:40

Yes, there was, indeed a dream. Pretty much everything else in the common story is, however, not quite accurate.

  • According to Mendeleev's statement to Prof. A.A.Inostrantsev, the dream DID help him somewhat to finalize/formalize the idea. The quote is indeed "a table where all the elements fell into place as required", but the drafts (v3) after that dream were not exactly the final form of the table.

  • It was a dream during the day, when he nodded off after several hours work on the topic.

  • The dream was not the main source of the table - nor was it the final version of it.

    Please note that Mendeleev was working on a way to pattern the elements very extensively for a long time, and in the days preceding 1869/02/17 he was playing with a "solitair" deck of cards with elements on it.

The full timeline and discussion with major list of russian sources can be found here:


Main source is "Трифонов Д. Н. Версия-2: к истории открытия периодического закона Д.И. Менделеевым // а) Вопросы истории естествознания и техники 1990, N2. C. 25-36; б) Там же, 1990, N3. C. 20-32." - "Trifinov D.N, Version-2: the history of discovery of Periodic Table by D.I Mendeleev". "History of natural sciences and technology", 1990, N2, pp. 25-36 and N3. C. 20-32."

A full biboliography: http://www.mendeleev.nw.ru/period_law/litera.html

Interestingly enough a similar story - this time confirmed 100% straight from the scientist's words - is associated with the discovery of the ring shape of benzene molecule. From Wiki:

Here Kekulé spoke of the creation of the theory. He said that he had discovered the ring shape of the benzene molecule after having a reverie or day-dream of a snake seizing its own tail (this is a common symbol in many ancient cultures known as the Ouroboros or Endless knot). This vision, he said, came to him after years of studying the nature of carbon-carbon bonds.

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