Language: an Introduction to the Study of Speech

According to Wikipedia: "Edward Sapir (January 26, 1884 – February 4, 1939) was a German-born American anthropologist-linguist and a leader in American structural linguistics. He was one of the creators of what is now called the Sapir-Whorf hypothesis. He is arguably the most influential figure in American linguistics, influencing several generations of linguists across several schools of the discipline."