The improver of natural knowledge absolutely refuses to acknowledge authority, as such. For him, skepticism is the highest of duties; blind faith the one unpardonable sin.

Teach a child what is wise, that is morality. Teach him what is wise and beautiful, that is religion!

Learn what is true in order to do what is right.

Every great advance in natural knowledge has involved the absolute rejection of authority.

The great tragedy of science - the slaying of a beautiful hypothesis by an ugly fact.

Thoughtfulness for others, generosity, modesty, and self-respect are the qualities which make a real gentleman or lady.

I do not say think as I think, but think in my way. Fear no shadows, least of all in that great spectre of personal unhappiness which binds half the world to orthodoxy.