The existing scientific concepts cover always only a very limited part of reality, and the other part that has not yet been understood is infinite.

Every tool carries with it the spirit by which it has been created.

Even for the physicist the description in plain language will be a criterion of the degree of understanding that has been reached.

Whether we electrons, light quanta, benzol molecules, or stones, we shall always come up against these two characteristics, the corpuscular and the undular.

Only a few know, how much one must know to know how little one knows.

The reality we can put into words is never reality itself.

It seems sensible to discard all hope of observing hitherto unobservable quantities, such as the position and period of the electron... Instead it seems more reasonable to try to establish a theoretical quantum mechanics, analogous to classical mechanics, but in which only relations between observable quantities occur.