Well this is one of my favorite stories.
So Padmasambhava was hanging out with his girlfriend Yeshe Tsogyal. And he is being quite impressive on various topics.
So Yeshe Tsogyal goes, "There are some things you don't know yet."
So Padmasambhava is like "Yeah whatever surprise me." Or something.
And this is where she takes this razor thin knife and slits open her stomach, right there in the living room.
She pulls open the flesh. And inside are stars and galaxies and space. Not symbols of them but the actual ones.