It's a sort of catch all term. I've never understood it, and it seems to me that SD's approach is simply using it as a synonym for aesthetic, which doesn't seem to match other uses here.
As a catch all, it is just used to indicate concern with the mental, philosophical or mythical world as opposed to the material, physical, commercial and so on.
Whether or not you divide things into things perceived through the senses (physical) or the mind (spiritual) or not is itself a philosophical position, is it not?
Anyway, anyone describing themselves as spiritual and others as not (does anyone claim this?) is clearly full of hot air.
