Since the cycle of existence has no beginning, there is no sentient being we can point to and say, "That person has not been my mother in the past." Not only have they been our mothers in the past, but also they will be our mothers in the future. If you are able to develop deep conviction in this fact, it will be quite easy to recollect and reflect upon their great kindness and then develop the wish to repay their kindness.
— His Holiness The Dalai Lama, The Way to Freedom