There Must Be No Barriers To

J. Robert Oppenheimer wrote this in The Open Mind (1955), a collection of essays and lectures on science, society, and freedom of thought. The book was partly a response to the McCarthyism and security culture of the early Cold War that had culminated in Oppenheimer's own security hearing in 1954, where his loyalty was questioned and his security clearance revoked. He argued that scientific progress requires the freedom to ask uncomfortable questions without dogmatic constraint.