An English translation of a work by Cyprien Aroud, a French Vincentian missionary in China (1899-1928). The author's letters from his mission in Wenchow have been excerpted and published in France in 1933. They cover the years 1908 to 1919. A special interest of his is the development of lay catechists as teachers and guides of small Catholic communities. His rules lay out their responsibilities. His letters give a perspective on the details of mission life, and the text concludes with an essay on the joy of being a missionary. He had great hopes for the future of the Catholic Church in China. Biographical information about his collaborators, Europeans and Chinese, has been added in notes. The author's interest was in giving information to potential donors to the mission.