That's certainly a clear explanation of the mystical idea.

I don't think I'd say that neither the philosopher nor the mystic can "grasp" what the other is saying. On the contrary, we each grasp it via our perspectives. I'm not saying all perspectives are equally valid, by the way. But judging a whole perspective is harder than judging a particular proposition.

I have room for mysticism in my worldview, in the Kantian concept of the noumenon and in Lovecraft's cosmicism or cosmic horror (his dramatizing of some implications of philosophical naturalism). But I haven't had the kind of mystical experience that you describe. Whether anyone has had exactly that experience is largely what's in dispute here.

There's a difference, for instance, between intuiting that the facts extend beyond our simplifying conceptions, and experiencing something as it is in itself, with no cognitive filtering. That's just a pragmatic, Kantian point, and there's a tantalizing yearning for what might lie beyond, for facts which surpass human comprehension. That yearning, fear, or hunch isn't the same, though, as "perceiving the void out of which all beings emanate."

There's our disagreement, then. The mystic says it's possible to experience something without understanding it with concepts, models, values, worldviews, etc. Rather than saying the mystic is simply lying or confused, I'd say mysticism is an interpretation of something like that Kantian, cosmicist, pragmatic yearning for inhuman truth, for truth as a superintelligent being might grasp it.

But to grasp anything, you need a hand. And to perceive something, you need senses, while to understand something, you need a mind. Somehow, the mystical experience is supposed to be perception with no senses, and direct understanding with no reasoning or interpretation.

The question I'd want to ask is what the difference is between the mystical experience, and a mere dwelling on the intuition or suspicion that there's a world out there that can't be grasped by our cognitive tools. I share that intuition, but I wouldn't call it a mystical perception of reality. Is that just a notational difference?