In "Emile," Rousseau advances significant ideas about language, language learning and teaching: He posits a universal natural language that develops as the child matures; focuses on 'private' words invented by children, on the challenge facing children in their understanding of exceptions to general rules of the mother tongue and on recommended methods of teaching the mother tongue. The paper explores these notions, which feature at the end of Book I of "Emile." It seeks to explain and interpret them as postulations regarding language, language learning and teaching and, moreover, to show how they relate to Rousseau's general principles of education.