The incontestable truth is that America has been built up by optimists, not by pessimists, but by men possessing courage, confidence in the nation's destiny, by men willing to adventure, to shoulder risks terrifying to the timid.
Hence, even in the domain of natural science the aid of the experimental method becomes indispensable whenever the problem set is the analysis of transient and impermanent phenomena, and not merely the observation of persistent and relatively constant objects.
