Dmitri Mendeleev

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

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.

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.

America will never be destroyed from the outside. If we falter and lose our freedoms, it will be because we destroyed ourselves.

Nothing that is worth doing can be achieved in a lifetime; therefore we must be saved by hope.