Who said "Courage is required to challenge established thought."?

This quote is attributed to Karl Landsteiner.

Courage is required to challenge established thought. - Karl Landsteiner

"Courage is required to challenge established thought."

Karl Landsteiner Courage

Immunologist Austrian-American 1868–1943

"Science is organized knowledge."

"The unknown is always feared."

"Discovery requires curiosity and patience."

"Blood types reveal the hidden connections between humanity."

"Never let fear stop you from chasing your dreams."

"Courage is being afraid but doing it anyway."

"Sometimes you gotta do what you gotta do."

"Sometimes you have to be the monster to stop the monsters."