We all carry around with us an idea of how the world works. This idea isn’t necessarily super detailed, but it does lay down the general guidelines for what we deem possible in the world and what we deem impossible.
For example: I am an atheist. This means that I don’t believe it’s possible that a supernatural being may, from time to time, intervene in human affairs (in response to a petitioning with prayer, for example), if for no other reason than that I believe such beings to be, all interventions aside, impossible.
Nevertheless, it doesn’t take much reflection to realize that no matter how sophisticated one’s notion of the world’s machinations, there is always something that one just doesn’t yet get or know about the world.
If we ever experience something like a revelation, then, what gives such revelation its jarring force is the way in which it reveals a fundamental and unsuspected truth about how the world works: that the imagined impossible is, astonishingly, possible.
And sometimes the realization of this possibility is nothing short of apocalyptic.