In this book, Massimo Introvigne restores credit to John Nelson Darby and his movement, and places them in a contemporary sociological framework based on Introvigne's participant observation in Brethren communities. The modern-day Plymouth Brethren emphasize sola scriptura, the belief that the Bible is the supreme authority for church doctrine and practice. Brethren see themselves as a network of like-minded independent assemblies rather than as a church or a denomination. The movement has also refused to take any formal denominational name; the title "the Brethren" comes from the Biblical passage "one is your Master, even Christ; and all ye are brethren" (Matthew 23:8). The Plymouth Brethren offers a typology of differing branches of this reclusive movement, including a case study of the "exclusive" branch known as the Plymouth Brethren Christian Church, and reveals the various ways in which Brethren ideas have permeated the modern Christian world.