What IS spiritual, anyway?

I caught a bit of an old talk by Alan Watts on the radio yesterday.  He was re-defining spirituality in an interesting way.  We usually think of abstractions as more "spiritual" than concrete reality, but he says it is just the opposite.  Abstractions are nothing but thoughts -- attempts to pin things down and define them.  And when we label our physical world or physical events, that too is a way of limiting.  We think once we have found a label to attach, we "understand" something, but the label, of course, doesn't capture the physical object or event at all.  But if we set the label aside, then we can see that the physical world is that which can never be limited or understood. It is, in fact, all of those things that we sometimes think of God or Spirit as being.  The world itself is plenty spiritual enough as it really is, if we can experience it as it really is.