Bernard tended to admire philosophers who were outside the mainstream. He discovered Nietzsche when he was already well advanced in philosophy, and though he was contemptuous of Nietzsche’s looseness at first, he became as much a follower of Nietzsche as he was capable of being of any other philosopher. He once said to me about Nietzsche that he thought it was ‘about 80% true’. I cannot imagine any other philosopher of whom Bernard would say that. I think he especially liked Nietzsche’s cynicism about mainstream academic life and academic philosophy. (p.188)
What intrigues me the most is certainly Williams's claim that what Nietzsche says is "about 80% true". That's an unusually strong claim for any philosopher to make about any other philosopher. Another fascinating fact here, and a related one, is that Williams "was contemptuous of Nietzsche's looseness at first". What the phrase "at first" implies is not that Williams ceased to think Nietzsche's thinking was loose after he became a follower of Nietzsche; rather, it implies that he was not contemptuous of Nietzsche's looseness anymore. Williams admired Nietzsche in spite of his looseness.
I did not consider the possibility that Williams ceased to think Nietzsche's thinking was loose for the simple reason that Nietzsche's looseness is conspicuous. Beyond Good and Evil 267 is a perfect example:
The Chinese have a proverb that mothers even teach children: siao-sin — "make your heart small!" This is the characteristic fundamental propensity in late civilizations: I do not doubt that an ancient Greek would recognize in us Europeans of today, too, such self-diminution; this alone would suffice for us to "offend his taste." —
"Siao-sin" is presumably a transliteration of the Chinese expression "小心". Not only does it not mean "make your heart small", it is not a proverb either, and hence not "a proverb that mothers even teach children". Although "小" means "small" and "心" means "heart", "小心" does not mean "small heart"; it means "be careful", which does not seem to have anything to do with "self-diminution". Such a mistake could have been avoided easily.
But perhaps Nietzsche simply didn't care — it's just a mistaken example; he's not using it as evidence to support his view. If he was right about "the characteristic fundamental propensity in late civilizations", i.e. self-diminution, it would not be difficult for him to find correct examples. For Nietzsche, insights first, examples later.