"A Key Into the Language of America, or an Help to the Language of the Natives in that part of America called New England" by Roger Williams is a linguistic study published in 1643. This groundbreaking work documents Native American languages in colonial New England, primarily Narragansett. Written by a banished Puritan who founded Rhode Island, the book serves multiple purposes: championing Indigenous land rights, countering rival colonial claims, and celebrating aspects of Native culture Williams found superior to European ways. It introduced enduring words like "moose" and "moccasin" into English.
Preceded by a "Sketch of the life of Roger Williams." Wikipedia page about this book: en.wikipedia.org/wiki/A_Key_into_the_Language_of_America