. . . "my ideal of a scientific man, accepting nothing upon authority, but putting every scientific theory to the severest test. . . . I hope I have learned from Professor Ludwig's precept and practice that the most important lesson for every man of science, not to be satisfied with loose thinking and half-proofs, not to speculate and theorize but to observe closely and carefully."
-William Henry Welch, as quoted in John Barry's The Great Influenza: The Epic Story of the Deadliest Plague in History