Every science begins with the observation of striking events like thunderstorms or fevers, and soon establishes rough connections between them and other events, such as hot weather or infection. The next stage is a stage of exact observation and measurement, and it is often very difficult to know what we should measure in order best to explain the events we are investigating. In the case of both thunderstorms and fever the clue came from measuring the lengths of mercury columns in glass tubes, but what prophet could have predicted this? Then comes a stage of innumerable graphs and tables of figures, the despair of the student, the laughing-stock of the man in the street. And out of this intellectual mess there suddenly crystallizes a new and easily grasped idea, the idea of a cyclone or an electron, a bacillus or an antitoxin, and everybody wonders why it had not been thought of before.
- J.B.S. Haldane, “The Future of Biology”