enturies ago, people believed that a person's image in a mirror was actually a reflection of the person's soul (much like the way Native Americans felt that a photograph stole part of their soul and why they resisted being photographed). Further, this is why vampires can't see themselves in the mirror--they have no soul. Anyway, believing that their soul was in the mirror, breaking a mirror meant that a part of the soul would not be able to reunite with the body. Obviously, without a portion of the soul, a person would be in for some bad luck. The seven years thing comes from the Romans. They believed that a person's health and fortune changed every seven years.