The Boasians' inductive methods and aversion to comparison led them to emphasize those areas of human behavior and thought that were least amenable to theorizing. Their ethnographic descriptions reveled in the uniqueness of each cultural tradition, upheld as the product of local history and circumstances that remain largely unknowable to the contemporary observer. Equally dire fears about "absorbing semi-civilized Catholic states" into the United States repeatedly prevented American presidents from pursuing annexation of Central American and Caribbean territories, even though this would be the logical consequence of the American principle of representative democracy. Contrary to Smith's and Perry's imaginative thesis, there is no credible evidence that the ancient Egyptians ever visited the New World. These are nonetheless amazingly persistent ideas, variants of which have enjoyed a tenacious following in popular culture. Finally, Boas is credited with developing the concept of cultural relativism.