When Guru Padmasambhava is the teacher of the samye ling monastery
The tibet king at that time had a newborn princess .
However ,the princess died suddenly of a illness at the age of 2 .
The tibet king was sad, and ask Guru what was the reason for the princess early death.
Guru Padmasambhava told him that when the samye ling monastery was in construction ,tibet king came to supervise the construction .A kind king who never killed any insects .
Then a fly flew around tibet king and make him irritated .when the fly landed on his right shoulder for a rest ,the king raise his left palm to hit the fly.the fly died and the King simply brushed it off
It is this reason ,the fly reborn as a princess ,as the fly rejoice in the building of monastery ,but the little scant regard for the fly life ,transformed into a karmic affliction that being reborn as a princess of tibet king