Excerpts from Books and Wikipedia
"Mendeleyev's table demonstrated recurring or periodic, properties in chemical elements. The elements were listed in order of increasing atomic number, with elements demonstrating similar chemical properties arranged in vertical columns." [Furtado: 1001 Days] "I saw in a dream a table where all elements fell into place as required. Awakening, I immediately wrote it down on a piece of paper, only in one place did a correction later seem necessary." [Wikipedia: Mendeleev]