Is and Isn't
or
A Clarification to that Material Only Fellow Who's Putting Down Religion and Spiritual Stuff while Just Seeing the Superficial Literal Side not Taking to Heart the Bard's Well-penned More Things that are Dreamt of in your Philosophy

You don't know what it is

You just know what it isn't

Which it isn't

But that isn't to say

There isn't what is

Which isn't what it isn't

Though what it is isn't an is

Or a what or an it and isn't an isn't

Is the is the is of the isn't

And the isn't the isn't of is