Quote from Mendeleev himself: "I saw in a dream a table where all the elements fell into place as required. Awakening, I immediately wrote it down on a piece o

Quote from Mendeleev himself: "I saw in a dream a table where all the elements fell into place as required. Awakening, I immediately wrote it down on a piece of paper." This is fascinating to me -- Our brains continue working during our sleep on problems we think about during our day!