According to another belief,breaking a mirror brings seven years of bad luck. If a mirror breaks, you must take the pieces out of the house quickly and bury them. Before the invention of mirrors , people must have first seen their own images in water. If a person's image was distorted by the water,it meant that bad luck would follow. When glass mirrors came into use, the bad luck became associated with breaking a mirror , rather than with the movement of water. If was believed that the person's image was shattered when the mirror broke.historians think that the number seven might have come from a roman belief. The romans thought that a person's body renews itself every seven years.