“The most important ingredient in any expert system is knowledge,” wrote three eminent scientists who work on expert computer systems (Bruce G. Buchanan, Randall Davis, and Edward A. Feigenbaum). “Programs that are rich in general inference methods—some of which may even have some of the power of mathematical logic—but poor in domain-specific knowledge can behave expertly on almost no tasks.” Their conclusion: “In the knowledge resides the power.”
