For me, there are two kinds of Heinlein stories: the entertaining science-fiction-y adventures driven by intriguing plots, and the obnoxious, self-indulgent, slightly off-color “stories” that I find repellent. Happily, this book falls into the former category. The characterization isn’t great (I can’t say that I came to care for any of the characters with more than passing interest—and this goes double for any female characters), but that’s not Heinlein’s strength. Instead, this story is intriguing for its premise (lunar penal colony rebels against Terran overlords) and its deus ex machina (a massive computer that achieves sentience and aids the lunar rebels in their cause). In fact, it’s this computer (“Mike”) who exhibits the most personality of any character in the story.

The future envisioned by Heinlein, in which Terra ships its convicts to the moon to do manual labor and, critically, grow crops to feed the billions left on Earth, is both prescient and naive. There are reasons from basic chemistry why growing grain on the moon would be difficult or impossible (mainly, lack of fertilizer), and shipping it to Earth would almost certainly be prohibitively expensive, but this is a necessary component of the plot. However, Heinlein is very careful in his science about the moon itself, from descriptions of how new arrivals cope with the reduced gravity to the radiation perils of being on the surface when the sun is up. With respect to technology, the computer he imagines is spot-on in terms of today’s computer evolution (and he wrote this way back in 1966!). On the other hand, the computer’s leap to sentience is never really explained, and the rate at which it knocks down all of the Artificial Intelligence hurdles, from language skills to conversational context to humor to inference to simulating a video portrayal of its “self”, is pretty unbelievable. Still, with a healthy suspension of disbelief, it’s very enjoyable to watch. The only odd thing about this future techno-world, for today’s reader, is Heinlein’s failure to anticipate the Internet. Despite having regular space travel between Luna and Terra, and a sentient computer, the only way anyone has to communicate is via phone (voice, not data). All of the networking is done with phone lines and realtime conversations between people. No email, no net, no web. It feels a little strange (but Heinlein, of course, can be forgiven for not anticipating everything!).

The book also contains a good dose of political arguments about the best form of government, and a typical Heinlein exploration of alternative marriage forms. Good fodder for thought.

One style nit-pick: I’ve repeatedly encountered writing advice that warns against the use of dialect in stories. I can now see exactly why. The dialect used by the narrator was grating at first and remained annoying throughout the entire book, making me grateful whenever he was reporting anything anyone else said, just for the relief from his bizarre dialect. It was entirely unnecessary, too. The other language touches Heinlein added, like the hints of Russian influence in how people address each other, are nicely done.