The Common Rue (Ruta graveolens) is a species of rue grown as a herb. It is cultivated as both a medicinal herb, as a condiment, and to a lesser extent as an insect repellent. During the Middle Ages, rue was hung in doorways and windows to keep evil spirits out. It was thought to protect against plague. Early Christians used it as a tool for asperging during exorcisms and before performing Mass, and this herb is the only one that the Prophet Mohammed blessed. This herb was grown around Roman temples to Mars and is considered sacred to him as well as to Diana and Aradia. Rue was sometimes called witchbane because people carried bunches to keep off witches. and the expression "rue the day" is said to come from the practice of throwing rue at an enemy while cursing him.