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.
Dmitri MendeleevThe establishment of a law, moreover, does not take place when the first thought of it takes form, or even when its significance is recognised, but only when it has been confirmed by the results of the experiment.
Dmitri MendeleevWe must expect the discovery of many as yet unknown elements-for example, elements analogous to aluminum and silicon- whose atomic weight would be between 65 and 75.
Dmitri Mendeleev