The moral core has been strengthened by Taoism, which besides feminism is the other major influence on her work. Le Guin says her first memory of Taoism was of watching her father read a book with Chinese characters all over the cover -- "and I knew he didn't know Chinese." The book was Lao Tzu's Tao Te Ching.
Thus, it's hardly surprising that Le Guin's new novel, The Telling, should be inspired by Mao Tse-tung's attempt to destroy Taoism in China. Mao pretty much succeeded in his own country, eradicating three thousand years of spiritual tradition in the name of communism. This fact inspired Le Guin to write a story in which a time-honored religion is obliterated just as quickly and brutally.
Next to feminism, Taoism has been the system of thought that most influenced her work. It is most evident in the many stories in which her characters' strength lies not in their action but in their inaction. The principle of yin and yang operates in her work, and the traditional Western dichotomies -- black and white, good and evil -- become much more complicated and intertwined.