Slatta (2001) argues that the widespread popularization of Turner's frontier thesis influenced popular histories, motion pictures, and novels, which characterize the West in terms of individualism, frontier violence, and rough justice. Disneyland 's Frontierland of the late 20th century reflected the myth of rugged individualism that celebrated what was perceived to be the American heritage. The public has ignored academic historians' anti-Turnerian models, largely because they conflict with and often destroy the icons of Western heritage. However, the work of historians during the 1980s–1990s, some of whom sought to bury Turner's conception of the frontier and others who have sought to spare the concept while presenting a more balanced and nuanced view, have done much to place Western myths in context and rescue Western history from them. 
Book II of the Essay sets out Locke's theory of ideas, including his distinction between passively acquired simple ideas, such as "red," "sweet," "round," etc., and actively built complex ideas , such as numbers, causes and effects, abstract ideas, ideas of substances, identity, and diversity. Locke also distinguishes between the truly existing primary qualities of bodies, like shape, motion and the arrangement of minute particles, and the “secondary qualities” that are "powers to produce various sensations in us" ( Essay, II. ) such as "red" and "sweet." These “secondary qualities,” Locke claims, are dependent on the “primary qualities.” This part of Locke’s thought would be sharply and famously criticized by Berkeley, who argued that there was no basis for a distinction between primary and secondary qualities and for asserting that primary qualities were any more “real” than the secondary ones. The weak point in Locke’s thought is that, in his own words, the substrate of those primary qualities, substance , is a “I know not what.” In other words, Locke is convinced that there must be something (substance) that is the foundation of objective existence and carries the primary qualities, but he is unable to further define it based on his empirical method.