Introducing into scholarship new sources of the Times of Troubles is determined by the demands and relevance of the research regarding one of the most significant periods in the history of Russian, the study of social-class relations, norms of everyday behavior, and family and kinship ties in Russia at the beginning of the 17th century. The discussion of the issue in the paper also stems from the necessity of extending linguistic knowledge and knowledge of sources about pre-national development of the cultural and linguistic situations, and their manifestation in real texts demonstrating variants of written and oral language culture of this epoch. The authors have analyzed and published three unknown letters from the Trinity Lavra of...