About 1932 one of Sapir's students at Yale, Benjamin Lee Whorf drew on Sapir's ideas and began an intensive study of the language of the Hopi Indians of Arizona. Whorf's brilliant analysis... seemed to support the view that man is a prisoner of his language. Whorf emphasized grammar—rather than vocabulary, which had previously intrigued scholars—as an indicator of the way a language can direct a speaker into certain habits of thought.

Word Play (1974)