Why do mistakes happen

Mistakes come from people bringing their ego, their personal feelings (likes and dislikes), their sense of prestige or their convenience, pride, sense of possession, etc. into the work. The right way is to feel that the work is the Mother’s—not only yours, but the work of others—and to carry it out in such a spirit that there shall be general harmony. Harmony cannot be brought about by external organisation only, though a more and more perfect external organisation is necessary; inner harmony there must be or else there will always be clash and disorder.

Ref: The Mother with Letters on the Mother