In an atheistic world, or at least in what passes for a scientific one, space is just real estate that no one wants except, maybe, to pass through on the way to somewhere else, but C. S. Lewis doesn't live in that world (though passes through it) thus it is not surprising that his sci-fi looks more like theology than like engineering. Still, he remains a logical kind of guy and wants to explain things in a way that a rational hnau (or, say, man) would understand. I've barely begun Paradise Lost (it's on my "currently reading" shelf, which means I hope to get back to it someday) but know enough to realize that Earth, the Silent Planet, remains mute because it is in quarantine for its therein described fallen state and that the other non-fallen planets are eager to understand what is going on there (I think they are concerned for us.) Earth and its inhabitants are not so much evil, which is to say unredeemable, as bent, which means they can than presumably be unbent (perhaps by pfifltriggi) and join the non-silent plants someday.

Maybe you're better off not knowing all this going in (I didn't) or maybe it doesn't much matter but he unfolds it nicely and I didn't feel preached to enough of the time to give it 4 stars (but a little bit so it must fall short of 5.)

Having just before this read Jane Austen's Emma, I'll add that being preached to, which I complain about in the previous paragraph, at an earlier time in Earth's history, lacked the negative connotations I am attributing to it, but perhaps all that should go in a review of Emma (which I haven't written yet.)

I should mention, in the interests of putting my point of view in context, that the is the first C.S. Lewis book I've actually completed, having abandoned a few others (most recently, The Screwtape Letters) for reasons I no longer remember. In addition, I confess to some sympathy for the Abrahamic religions though think they all went astray at points.