"One should as a rule respect public opinion in so far as is necessary to avoid starvation and to prevent oneself from being cast into prison, but anything that goes beyond this is voluntary submission to an unnecessary tyranny."
"Do not fear to be eccentric in opinion, for every opinion now accepted was once eccentric."
"The only thing that will redeem mankind is cooperation."
"What is wanted is not the will to believe, but the wish to find out, which is the exact opposite of the will to believe."
"Fear is the main source of superstition, and one of the main sources of cruelty."