The Benedictines, officially the Order of Saint Benedict, are a mainly contemplative monastic religious order of the Catholic Church for men and for women who follow the Rule of Saint Benedict. The male religious are also sometimes called the Black Monks, in reference to the colour of their religious habits, in contrast to other Benedictine orders such as the Olivetans, who wear white. They were founded in 529 by Benedict of Nursia, a 6th-century Italian monk who laid the foundations of Benedictine monasticism through the formulation of his Rule. Benedict's sister, Scholastica, possibly his twin, also became a religious from an early age, but chose to live as a hermit. They retained a close relationship until her death.