Humanity may endure the loss of everything; all its possessions may be turned away without infringing its true dignity - all but the possibility of improvement.

Nothing is more destructive of individual character than for a man to lose all faith in his own abilities for the prosecution of his work.

He who is firm in will molds the world to himself.

I know what I can know, and am not troubled about what I cannot know.

There are two great classes of men: the people and the scholars, the men of science. For the former, nothing exists but that which directly leads to action. It is for the latter to see beyond. They are the free artists who create the future and its history, the conscious architects of the world.

The person who doubts there is an external world does not need proof: he needs a cure.

All death in nature is birth, and at the moment of death appears visibly the rising of life. There is no dying principle in nature, for nature throughout is unmixed life, which, concealed behind the old, begins again and develops itself. Death as well as birth is simply in itself, in order to present itself ever more brightly and more like to itself.