Howard Pyle was an American Illustrator and writer, often called the "father of American illustration." His 1883 classic, The Merry Adventures of Robin Hood, remains in print to this day and his four-volume set on King Arthur cemented his reputation. He wrote over two hundred texts and and published more than three thousands illustrations.
In 1894 he began teaching illustration and in 1900 he founded his own school of art and illustration. Among his many famous students was N.C. Wyeth. Among his pictures are some drawings of a Brethren love feast, an aged couple and a young couple on the way to worship and individual pictures of sisters at worship.
The drawings of the Brethren were published in 1889, along with an article of the Brethren as a young writer at the age of 27 for Harper's Magazine. The assignment by his editor to spend some time among the Pennsylvania Dutch and initially viewed with some apprehension. Pyle confessed in a letter to his fiancee that he was at first put off by the German Baptist Brethren, but soon learned that they were "smarter than they looked."
In his article he described the Brethren as follows:
Here on meets the Dunker per se in every by-road and lane - men with long beards and flowing hair parted in the middle. At the farm-houses are pleasant, matronly faces, stamped with humility and gentleness, with an air of almost saintly simplicity is given by the clear-starched cap, the hankerchief crossed on the breast; the white apron, and the plain gray or drab stuff of the dresses.
The style of living of these good people, their manners and customs, are of the most primitive type. Their aim is to imitate the early Christians in their habits of life as well as in their religious tenets. There is absolutely no distinction of caste among them.
... Their dress is of the simplest description, quaint and old-fashioned in its cut; they offer no resistance to injuries; they observe no conformity with the world and its manners and customs; they refuse to take oaths in courts of law.... They are called Dunkers ... They also sometimes call themselves "God's Peculiar People."
Sources: Wikipedia, Howard Pyle
The Brethren Encyclopedia
Harper's Magazine