The book "Letters of John Calvin, Volume I. Collected from the original manuscripts and corrected with historical notes" is a valuable collection of letters from the famous reformer and theologian John Calvin, who became famous for his activities in Geneva and made a significant contribution to the development of the Protestant movement. In this book, the reader will have the opportunity to see Calvin in the role of a postman, communicating with different personalities and expressing his thoughts and ideas from different areas of life. Editorial notes complement the text of the letters and contextualize them in the historical period, making this book not only an interesting source for studying the life of Calvin himself, but also an important testimony of the Reformation era.