Dmitri Mendeleev

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.

We 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.

The magnitude of the atomic weight determines the character of the element, just as the magnitude of the molecule determines the character of a compound body.

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

It is the function of science to discover the existence of a general reign of order in nature and to find the causes governing this order. And this refers in equal measure to the relations of man - social and political - and to the entire universe as a whole.

Elements which are similar as regards their chemical properties have atomic weights which are either of nearly the same value (eg. Pt, Ir, Os) or which increase regularly (eg. K, Ru, Cs).

I have achieved an inner freedom.

Pleasures flit by - they are only for yourself; work leaves a mark of long-lasting joy, work is for others.

I want you to have this feeling too - it is my moral responsibility to help you achieve this inner freedom.

We could live at the present day without a Plato, but a double number of Newtons is required to discover the secrets of nature, and to bring life into harmony with the laws of nature.

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

The most all penetrating spirit before which will open the possibility of tilting not tables, but planets, is the spirit of free human inquiry. Believe only in that.