 So why have biochemists emphasized this experiment so much? Perhaps the reason is not merely the beauty of the experiment or its pedagogical value. From a methodological point of view, the experiment stands out from other experiments in the amount of control that biochemists had of what was going on in their test tubes. Because it was an artificially created system assembled from purified components, the biochemists knew exactly what they had put in there, making it less likely that they were deceived by traces from the enormously complex system from which these biochemical agents were derived. On such an interpretation, the experiment was not crucial in Duhem’s sense of ruling out all alternative hypotheses. Rather, what distinguishes it is that, within the body of evidence that supported Mitchell’s hypothesis, this one reached an unprecedented standard of experimental rigor, making it more difficult for opponents of Mitchell’s hypothesis to challenge it (see Weber 2005, Chapter 4).