A small sect of fewer than 20,000 in the UK, and approximately 100,000 in the USA, Quakers have produced a disproportionate number of eminent thinkers, scientists, businessmen, and their teachings have been widely influential and become mainstream. Best known as pacifists, Quakers have always been at the forefront of social justice and conflict resolution, once being leaders in the abolitionist movement on three continents and, more recently, key...