What do we really know about Mendeleev’s dream of the periodic table? A note on dreams of scientific problem solving.

Abstract

As is well known, some dreams have been instrumental in important scientific discoveries. Kekule's dream of the whirling snakes is probably the most famous instance though there was apparently no public written record of it until some 28 years later. Loewi, even in his own autobiographic material, appears never to have provided a written report of the dream that led him to carry out the experiment demonstrating the chemical transmission of nerve impulses to a frog's heart. Mendeleev's dream of the periodic table of elements in its completed form is apparently specious, despite repeated citations. Not only is there no dream report but evidence rests on a colleague's second-hand account. Kedrov's examination of archival material indicates (1) that Mendeleev had already discovered the periodic table before the alleged dream took place; and (2) that a dream quite plausibly occurred somewhat later that depicted an improved representation of the periodic table. Kedrov's reconstruction is consistent with other accounts of dreams and the process of scientific discovery.