Long before mirrors were invented, people used to see
their reflections in pools of water and since they had no
scientific knowledge at that time, they believed the
reflection was the soul to their other self, otherwise known
as the spirit world. Narcissus was supposedly bewitched by
his own reflection in a pool of water, and magic powers are
ascribed to mirrors in fairy tales.
From earliest times, many people believed that by
interfering with their reflection in the water, they would
injure their soul. Hence, when the first mirrors arrived on
the scene and the ability to "break a mirror" became real,
it was thought that the "other self" was harmed.
The myth about bad luck for seven years after breaking a
mirror came about from a Roman belief that life renewed
itself every seven years. Because a broken mirror meant bad
health, it was thought that the person who broke the mirror
would therefore require seven years to heal.
Man-made mirrors have been in existence since ancient times.
The first mirrors were made out of sheets of polished metal
and were used almost exclusively by the ruling classes.
Appearance often reflected, and in some cases determined,
position and power in society, so the demand for looking
glasses was high, as was the demand for the improvement of
mirror-making techniques. Silvering—the process of coating
the back of a glass sheet with melted silver—became the most
popular method for making mirrors in the 1600s.