We all carry around a default metaphysics -- a deep belief structure about the nature of reality. It is possible to transcend these beliefs in a way that allows you to grok (not just understand) that they're not supported in the way we normally assume. That transcendence is often accompanied by an overwhelming gratitude, joy, awe, and wonder that are normally inaccessible.

Of course, our belief structures almost always come rushing right back, and so we interpret the experience in terms of our metaphysics ("oh, it was just brain chemicals"), but part of us understands the sense in which this is just a story.