Hans Christian Andersen
The Emperor's New Clothes
Two weavers promise an Emperor a new suit invisible to those unfit for their positions, stupid, or incompetent. The Emperor parades before his subjects — and no one dares to say that they don't see any clothes, until a child cries out, "But he isn't wearing anything at all!"
Moral — Most boardrooms have the child in them. The job of an advisor is to keep that voice in the room.