In 1666, when Philipp Jacob Spener (1635-1705) assumed office as pastor and senior of the Frankfurt ministerial, he had no parish experience. What he did bring was a thorough religious and theological education. This put him in a position to offer a candid diagnosis of the spiritual condition of Christianity in Germany and to offer practical suggestions for confronting its decline. This marked the beginning of Pietism, and the emergence of forces which would make Pietism into an extraordinary movement of religious and cultural renewal far beyond German borders. It was Spener's singular achievement that he not only was aware of the scholarly developments of his time, but that he assessed their relevance for academic theology and for the life of the church. This selection of Spener's Latin letters, some of them translated for the first time, provides first hand accounts of this crucial period in the formation of Pietism.