The relation of language and mind has interested philosophers for many centuries. 61 ) The Greeks assumed that the structure of language had some connection with the process of thought, which took root in Europe long before people realized how diverse languages could be. Only recently did linguists begin the serious study of languages that were very different from their own. Two anthropologist-linguists, Franz Boas and Edward Sapir, were pioneers in describing many native languages of North and South America during the first half of the twentieth century. 62) We are obliged to them because some of these languages have since vanished, as the peoples who spoke them died out or became assimilated and lost their native languages. Other linguists in the earlier part of this century, however, who were less eager to deal with bizarre data from "exotic" language, were not always so grateful. 63)The newly described languages were often so strikingly different from the well studied languages of Europe and Southeast Asia that some scholars even accused Boas and Sapir of fabricating their data. Native American languages are indeed different, so much so in fact that Navajo could be used by the US military as a code during World War II to send secret messages. Sapir’’s pupil, Benjamin Lee Whorf, continued the study of American Indian languages. 64 ) Being interested in the relationship of language and thought, Whorf developed the idea that the structure of language determines the structure of habitual thought in a society. He reasoned that because it is easier to formulate certain concepts and not others in a given language, the speakers of that language think along one track and not along another. 65 ) Whorf came to believe in a sort of linguistic determinism which, in its strongest form, states that language imprisons the mind, and that the grammatical patterns in a language can produce far-reaching consequences for the culture of a society. Later, this idea became to be known as the Sapir-Whorf hypothesis, but this term is somewhat inappropriate. Although both Sapir and Whorf emphasized the diversity of languages, Sapir himself never explicitly supported the notion of linguistic determinism.