In [b:Classics in the Classroom|8676583|Classics in the Classroom|Michael Clay Thompson|http://d.gr-assets.com/books/1356705416s/8676583.jpg|13548503] MCT talks about practicing disassumption - "discovering and escaping limiting or obstructing assumptions" - while reading, analyzing and discussing literature. Disassumption is inescapable while reading The Left Hand of Darkness. As you read you are forced to recognize that when you hear or read the word "he" or some other masculine word like "king" you don't just register third person singular masculine (or third person singular masculine ruler). These words come with a package of assumptions attached - has male genitalia, cannot get pregnant, does not menstruate, does not lactate, etc. One might even bring with the word "he" such assumptions as - short hair, only cooks on grill, handy, is married to a woman, makes more money than wife, etc. But when you read about the king being pregnant, it is a jarring experience in which you are forced to shut down for a minute, recognize that you brought a package of assumptions along with the word "king" and escape them.
Additionally, Le Guin explores prejudice against women, culture gaps and the difficulty of bridging them, politics, nationalism, greed, selfishness and pride, loyalty and friendship - all while giving the reader a tour of another planet - the climate and geography and the culture's politics, food, dress, myths and customs.