I rather like the introduction of the midi-chlorians in Star Wars.
So do I. I love the analogy of the biological with the spiritual. Mitochondria in real life are amazing, thought-provoking things -- symbiotic organisms to which we owe our very existence, at once separate life forms and inseparable parts of ourselves. Without the energy -- the "life force" -- they provide, we couldn't exist. I think that introducing a more mystical analogue for the same thing -- symbionts on which living things depend for their connection to the spiritual force of the universe -- is a lovely idea, kind of poetic. It also ties nicely into the Eastern philosophical influences on Star Wars
. In Western thought, the physical and the spiritual are seen as separate and mutually exclusive realms, so the idea of something spiritual/mystical having a biological component is strange to us; but in Eastern thought, the physical and the spiritual are aspects of the same thing. Blending Asian-style mysticism with modern cellular biology is really quite clever. I think it's one of the only truly imaginative and original things George Lucas has ever thought of.
Really well stated, Christopher, I feel the exact same way.