During today's commemoration of the 175th anniversary of the restoration of the priesthood, this well-known scripture was cited repeatedly:
And I will give unto thee the keys of the kingdom of heaven: and whatsoever thou shalt bind on earth shall be bound in heaven: and whatsoever thou shalt loose on earth shall be loosed in heaven. (Matthew 16:19)
The part about sealing/binding I think I understand pretty well: it essentially means that ordinances, properly done and recorded, are considered valid and create ties that can continue beyond this life. But I don't have a good understanding of the part about loosing. When we seal something, we do so with an ordinance. Are there ordinances that serve a loosing function? When a sealing is cancelled, is there an ordinance of cancellation of sealing, or is the cancellation simply recorded? How is the priesthood involved in loosing?