While some miracles are intended to serve as signs, this should not be taken to mean that there is no other reason for why a particular miracle occurred. God flipping the pyramids upside down would indeed be a “sign”, but this sort of event is not at all likely to occur for the simple reason that there is no love in such an ostentatious display. There are many Saints of whom little or none is written who experienced private supernatural phenomena. A miracle can serve as a sign, but that is not necessarily the primary reason why it happens. When a mystic survives on solely the Eucharist for years on end, it isn’t because God decided, “Okay, I’ll let her survive without food or water for several decades, that’ll make the rest of them faithful.” No, there is first and foremost a divine principal behind the phenomena. If a holy person can live on communion, it is because the Eucharist is actually nourishing them. They are receiving its full benefits, more than any of us receive, and thus they can both spiritually and physically live on the Body of Christ. In this case, the miracle does not depend on whether they are observed or not. Similarly, if a holy person levitates, it isn’t primarily because God wants to impress us. Even demons can make people levitate. If a holy person levitates, it is because their spiritual longing for Heaven is* actually* drawing up “towards” Heaven. There is love but there is also a logical underpinning to every miracle.