The book "Excerpt from the Grammar of Mutsun" by Felipe Arroyo de la Cuesta is a study that focuses on the language and grammar of Mutsun, the language of the Indian people who once inhabited the territory of South America. In his book, the author examines in detail the phonetics, morphology and syntax of the Mutsun language, helping the reader to better understand its structure and features. This book will be a useful source of information for linguists, ethnographers, and anyone interested in studying the languages of Native American cultures.