Raziel gave them to the Nephilim not only for individual use, but also in case of dire emergency, when he would heed their call only once; when used all together, the Instruments would summon the Angel.
A thousand years ago, the Angel Raziel was summoned during a time when the Incursion was at its peak, when a huge wave of demons crossed dimensions into the human world. Raziel rose from Lake Lyn and mixed some of his own blood with the blood of Jonathan in a Cup, which became known as the Mortal Cup, and gave it to him to drink, entrusting with him the responsibility of creating more of his kind by letting others drink from it. Along with the Cup, Raziel also gave him the Mortal Sword.
For years, however, the Mortal Mirror was believed to be lost. It was in 2007 when it was revealed, after being deduced by Hodge Starkweather, that it was in fact Lake Lyn in Idris. The same year, the Mortal Instruments were used by Valentine Morgenstern to summon Raziel. Because of this, the Instruments can apparently no longer be used to re-summon him.
- Each of the first three books in The Mortal Instruments series focus on one specific instrument: City of Bones on the Mortal Cup, City of Ashes with the Mortal Sword, and City of Glass on the Mortal Mirror.
- The original inspiration for the Mortal Instruments were the Imperial Regalia of Japan, which consist of a sword, a mirror, and a jewel.