When the immediate disciples of the saint had become an order bound by the religious vows, it became necessary to provide for the great body of laity, married men and women, who could not leave the world or abandon their avocations, but still were part of the Franciscan movement and desired to carry out in their lives its spirit and teaching. And so, probably in 1221, St. Francis drew up a Rule for those of his followers who were debarred from being members of the order of Friars Minor. At first they were called "Brothers and Sisters of the Order of Penance"; but later on, when the Friars were called the "First Order" and the nuns the "Second Order," the Order of Penance became the "Third Order of St. Francis" whence the name Tertiaries: this threefold division already existed among the Humiliati. Nicholas IV introduced unity of rule and of direction into the Third Order, which henceforward was entrusted to the care of the Friars Minor.