Knowledge of the spoken language and its diversity ceased with the death of the last speakers of SNEA languages. Most had ceased to be functional, everyday languages of the Indian communities by the end of the eighteenth century, if not sooner, and all were extinct by the dawning of the twentieth century. Most linguistic knowledge relies on word lists and passing mention in colonial sources, which can only provide very limited understanding. Written records do show some variation, but dialect leveling was brought about with the introduction of a "de facto" standard written language as used in Eliot's translation of the Bible and several primers and catechisms used to teach literacy, were produced with the aid of Indian translators, editors and interpreters from Natick, and was based on its speech.