There is nothing in this world that I fear to say.

The 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.

No law of nature, however general, has been established all at once; its recognition has always been preceded by many presentiments.

If all the elements are arranged in the order of their atomic weights, a periodic repetition of properties is obtained. This is expressed by the law of periodicity.

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.

Certain characteristic properties of elements can be foretold from their atomic weights.

The elements, if arranged according to their atomic weights, exhibit an apparent periodicity of properties.