I suspect what happened here (and possibly in other similar cases) is that some author glossed a body of work in a way that made sense in context, and others mistook it as a quotation. It's as if I remarked that Isaac Asimov said a lot of prescient things about robots, and people saw that and started quoting it:
> A lot of prescient things about robots.
> -- Issac Asimov
I find it fascinating how many interesting quotes turn out to be fabrications of unknown origin.