The book "Spiritual Reformers in the 16th and 17th Centuries" by the author Rufus M. Jones tells about the key figures who played an important role in the religious transformations of this era. The author explores the lives and ideas of such notable people as Martin Luther, Schweitzer, Giordano Bruno, Jean Calvin, and many others. Through the prism of their actions and views, the book offers a unique perspective on the development of Christianity in the 16th and 17th centuries. "Spiritual reformers in the 16th and 17th centuries" is a valuable source for understanding the history of religious movements and transformations of that period.