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

The edifice of science not only requires material, but also a plan. Without the material, the plan alone is but a castle in the air-a mere possibility; whilst the material without a plan is but useless matter.

I have achieved an inner freedom.

Knowing how contented, free, and joyful is life in the world of science, one fervently wishes that many would enter its portals.

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.

Work, look for peace and calm in work: You will find it nowhere else. Pleasures flit by -- they are only for yourself; work leaves a mark of long-lasting joy, work is for others.

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