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Dmitri MendeleevFebruary 1869 (by the Russian calendar of the time)

Did Mendeleev dream the periodic table?

One of the most repeated stories in science says the periodic table appeared to Mendeleev complete in a dream. The evidence says otherwise.

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The dream

Retold in our own words from the sources below, not quoted.

In the popular version, the Russian chemist Dmitri Mendeleev had spent days trying to arrange the known chemical elements in a meaningful order. Exhausted, he fell asleep and saw a table in which every element fell into its proper place. When he woke he wrote it down, and only one correction was needed later.

The story usually comes with a quotation in which Mendeleev himself describes the dream. That quotation cannot be traced to anything he wrote.

Where the story comes from

Mendeleev published his periodic system in 1869; it predicted undiscovered elements and became the basis of modern chemistry. The dream story was told by a colleague, the geologist Alexander Inostrantsev, long afterwards, and does not appear in Mendeleev's own writings.

His working drafts from the decisive day survive and have been studied closely, which is rare for a famous discovery and makes this story checkable.

How it has been read

Research

The psychologist George Baylor reviewed what is actually known and concluded that there is no dream report from Mendeleev himself. Drawing on the Soviet historian B. M. Kedrov's study of the manuscripts, he notes that the table was already worked out on paper before the supposed dream, and that at most a later dream may have shown an improved layout.

Questions for your own dreams

  1. Why do you think we love stories of discoveries made in one night?
  2. What have you worked out slowly that people assume came to you easily?
  3. Have you ever dreamed about a task you were stuck on, and did it help?

Had a dream that stayed with you?

Tell us your dream

Sources

Every reading on this page comes from these works. Page references have not all been checked yet; those still waiting are marked.

  1. George W. Baylor (2001). What do we really know about Mendeleev's dream of the periodic table? A note on dreams of scientific problem solving. Dreaming 11.

    cited, not reproduced

    • Cited at: whole article (reference not yet checked)

    Draws on B. M. Kedrov's study of Mendeleev's manuscripts.