The Lost History of Christianity: The Thousand-Year Golden Age of the Church in the Middle East, Africa, and Asia—and How It Died

by Philip Jenkins

Sufi derives from the Arabic word for “wool,” the material of an ascetic’s garment. This costume followed the practice of the Nestorian churches, whose bishops and higher clergy were expected to wear wool, rather than linen or silk, as a sign of simplicity and devotion.