Hypotheses are the scaffolds which are erected in front of a building and removedd when the building is completed. They are indispensable to the worker; but the worker must not mistake the scaffolding for the building.

I have always paid attention to the merits of my enemies, and found it an advantage.

Don't give us your doubts, gives us your certainties, for we have doubts enough of our own.

No one can take from us the joy of the first becoming aware of something, the so-called discovery. But if we also demand the honor, it can be utterly spoiled for us, for we are usually not the first. What does discovery mean, and who can say that he has discovered this or that? After all it's pure idiocy to brag about priority; for it's simply unconscious conceit, not to admit frankly that one is a plagiarist.

The affairs of the world are no more than so much trickery, and a man who toils for money or honour or whatever else in deference to the wishes of others, rather than because his own desire or needs lead him to do so, will always be a fool.

The most fortunate of men, Be he a king or commoner, is he Whose welfare is assured in his own home.

This is the highest wisdom that I own; freedom and life are earned by those alone who conquer them each day anew.