There is matter in the universe, and some of that matter is talking about where the matter came from. That's pretty much the most mind-blowing thing I can think of.
More serious answer: in the room right here with me now is a self-contained organic system, made of matter not inherently different from the stuff that makes up a star or a lump of rock, that hasn't been designed by any intelligent agency but already has an information-processing capability far in advance of the most powerful computer and the ability to learn any language that's ever been spoken. And a year ago it was a clump of cells invisible to the naked eye. To go hard Sagan for a moment, that's mind-blowing to me.
Maybe that's why I have no truck with 'mysticism',
per se - the real, material universe is mystical in and of itself.