Adolf von Baeyer Quote
Men who are capable of modifying their first beliefs are very rare. This ability was one of the reasons for the success of Claude Bernard and Pasteur. Out of a very vivid imagination they forged new hypotheses all the time but abandoned them with equal ease as soon as experience contradicted them.
In: Richard Willstätter, From My Life: The Memoirs of Richard Willstatter, Chapter 6 (p. 141)