Roman Superstitions
The Romans were well-known for their high level of superstition. This was mostly because they did not possess the science or knowledge to explain events that they classified as phenomena. They believed lightning was sent to them from the gods and that the future could be told from animal remains. Ghosts were a common belief. Every roman knew that these dark spirits lurked in houses where a vicious murder was committed. The half man half wolf monster known as the werewolf was believed to kill farmer's herds at night and then by morning transform back to a normal human. Bad luck was also a worry of the overly paranoid romans. They took special care to always cross a threshold with their left foot first. They also stayed clear of black cats and snakes for fear of imminent disaster. A nightmare was also a sure sign to be extra alert. Any natural disaster was said to be a warning from the gods or a sign that they were angry. One such case occurred when a vestal virgin, a highly important symbol of Rome, was struck by lightning. The people were sure that the reason for this was that that particular vestal virgin must have broken her vow of purity. The romans took no chances and burned two other virgins that they believed had also broken their vows when in reality they probably had not.
Romans also believed that at night strange and evil creatures known as vampires were thought to enter the house of a newly deceased and mutilate the corpse. Amulets and other supposed magical objects were worn to repel these creatures of the night. Children were often told stories to scare them into good behavior. Two examples of these fairy tale monsters were Mormo, a woman with donkey legs, and Lamia, who ate young children.
Against common belief not every roman suffered from a strong case of intense superstition. The upper class was often more informed and did not waste their time dwelling on trivial fears. They did, however, take heed to what was written in the Sibylline Books. These books were almost like a guide telling how to handle and interpret superstitions. Whenever a natural disaster, for example, would occur Romans would look to these books to learn why the gods were angry and what should be done to make them happy again.
http://www.roman-empire.net/religion/superstitions.html