Dmitri Mendeleev, a great Russian chemical scientist,  was obsessed with finding a logical way to organize the chemical elements. He wrote the elements’ names and the properties of every element on cards – one element on each card. He saw that atomic weight was important in some way, but he could not find a pattern. Convinced that he was close to discovering something significant, Mendeleev moved the cards about for many hours until finally he fell asleep at his desk. And his subconscious mind had done his work for him – Mendeleev saw a logical arrangement of the chemical elements in a dream.

Dmitri Mendeleev later wrote: “In a dream I saw a table where all the elements fell into place as required. Awakening, I immediately wrote it down on a piece of paper.”  >>>

Dmitri Mendeleev was a chemist of genius, first-class physicist, a fruitful researcher in the fields of hydrodynamics, meteorology, geology, certain branches of chemical technology. He  formulated the Periodic Law, created the periodic table of elements, and used it to correct the properties of some already discovered elements and also to predict the properties of eight elements yet to be discovered.