Charles Sanders Peirce
“The irritation of doubt causes a struggle to attain a state of belief.”
“The real is that whose characters are independent of what anybody may think them to be.”
“The production of belief is the sole function of thought.”
“The opinion which is fated to be ultimately agreed to by all who investigate is what we mean by the truth.”
“We have no power of thinking without signs.”
“Do not block the way of inquiry.”