text: The concept came with the beginnings of glass mirrors.  The process of silvering glass was difficult and very expensive.  The curse was set upon chamber maids and ladys-in-waiting so that they would be careful with their mistress's mirror.\nSome would have us believe that the seven years comes from the Roman believe that life had a seven year renewal cycle and breaking a mirror while looking into it would damage the seer for seven years.  I do not put much faith into this since most Roman mirrors were usually metal and most mirrors are not being stared into when they are broken (they are usually dropped while being transported).