The strength of historians' generalizations depends on the depth of examples from which they generalize. A number of works of American history demonstrate this point. Beard noted in his landmark work on the economic bases of the United States Constitution that "as in natural science no organism is pretended to be understood as long as merely its superficial aspects are described, so in history no movement by a mass of people can be correctly comprehended until that mass is resolved into its component parts" (253). But, as Beard himself wished to point out, there are distinct limits on how many of the individuals that make up such a movement can be known and how much detail will be available -- or even useful -- on each individual. Beard's famous study demonstrated how the prevailing view of the nature of an event could be radically altered by specific attention to the interests of the parties involved -- as revealed in the study of primary sources -- rather than merely accepting the historical actors' self-proclaimed evaluation of the event. The meaningful interpretation of historical events depends on mastery of the primary sources. Historiography that proceeds from preconceived notions without explicit attention to original sources tends, instead, to reflect the ideology of the original actors, of patriotic legend, or of previous historians, thereby obscuring rather than clarifying the meaning of events.
Later historians continued this attention to primary sources and specific interests and studied progressively smaller units in greater detail in order to revise previous historians' understanding of certain movements. Brown, for example, analyzed the true extent of democracy in pre-Revolutionary Massachusetts by studying the actual extent of adult male suffrage. And Countryman studied three groups of land rioters in the pre-Revolutionary eighteenth century in order to understand their relationship to urban mobs and their ...