I've been meaning to get around to reading something by Ursula K. Le Guin for a while now, and I honestly picked up the Left Hand of Darkness half out of a sense of obligation. It's one of those books I knew I should read, which doesn't always translate into books I want to read. [1. I feel the same way about Ender's Game, by the way, which I'm reading now because my little brother insisted.] I'm really glad I read this, though. And I'm eager to read more of Le Guin's work.[2. Which won't be for a while, because the next twenty or so books I'm reading are all by teachers at this year's Clarion, in case I get in.]
The general idea of the story is: Genly Ai, a human male envoy (the "first mobile") has come to a planet, Gethen, populated by a species of human that doesn't have two sexes, and doesn't have a gender binary. A big part of the appeal of this book is the astounding quality of the thought experiment, what would civilization be like without a sex divide? But that's not all worth reading in it.
Not totally spoilery content below, but with more information about what the book contains past the first couple chapters.
For clarity, I should explain: any given Gethenian is usually -- not asexual, but sexually dormant, and during their sexually active period may shift into either a male or female role. They neither have control over which way they shift on any given period of sexual activity, nor only ever shift into one sex or the other for their entire lives. If a Gethenian takes on the female role in one particular period of sexual activity, they may become pregnant, and for nine months plus nursing time their body remains more in a state like femaleness. This isn't a species with secret genders only expressed sometimes, it's a species where everyone has the same relationship to their sexual and procreative organs as everyone else.
It's genuinely striking, when you read this book, to keep noticing that it feels like half of a species is missing. Everyone is treated equally as full members of society, and you feel that sense that there's a second class missing. Genly consistently fails to acclimate to the fundamental differences between Gethenian civilizations and ours, and so did I. In that sense, it's very illustrative of humans' internalized sexism.[3. At first I wrote "Actual humans," but I don't want to suggest that the Gethenians aren't human. I was going for "non-fictional" but fell short.]
But I don't want to go on forever about the gender identity part of the book. I hope you read it, and everything I say about it will detract from its impact when you do.
The thing I liked best about the book, I think, was the backstory about how Genly got there. He represented the Ekumen, an interplanetary organization that primarily focused on organizing trade. Every planet they represented, though, was populated by humans, and every one discovered the way that Gethen was discovered, populated by humans of some kind or another.
The universe, we discover, was subject to some great trauma, and at some point before that, there were people who went to planets and abandoned groups of humans. Genly thinks it's likely that the Gethenians were an experiment performed by some unethical group, to remove sexual differentiation from humanity, populate a planet with them, and see what happens.
The narrative of the book comes entirely through two perspectives, Genly's field notes and the journal of Therem Harth rem ir Estraven, as well as a handful of stories from the Genethian oral tradition. I didn't really expect it to be, but the story that these narratives end up telling is enthralling in its own right. I was about two thirds of the way through the book before I realized that I cared more about what was going to happen to and between Genly and Estraven than I did about learning more about Gethen.
Altogether this is an incredibly good book, and I recommend it highly, and look forward to when I'm going to have the time to give it a second read.