The discoveries of the last couple decades are showing that properties of a self do actually inhere in matter, that matter seems to have properties of self-organization and life, even intelligence, consciousness. I can't say that science has proved these things, but it at least suggests the possibility. As we re-invest the world with sacredness, "spiritual" comes to mean something very different. If only a human being has these qualities, then spiritual work is inner. It's all about your own consciousness.