a mobile army of metaphors, metonyms, and anthropomorphisms--in
short, a sum of human relations, [sic] which have been enhanced,
transposed, and embellished poetically and rhetorically, and which
after long use seem firm, canonical, and obligatory to a people:
truths are illusions about which one has forgotten that this is what
they are.
^^^^^^ CB: Yes, this is a shake up that elementary philosophy gives us, but doesn't Bishop Berkeley give the same shake up way before N ? "There is no objective reality; everything is thought." It is the kernel of truth in idealism. But ultimately , if taken as an absolute truth itself, it leads to total paralysis and depression, solopsism. This is particularly true of subjective idealism Perhaps N.'s personal life history is relevant here.
The above may be an "objective idealist" assertion, a la Plato and Hegel's idealism, as I read it.
The more mature way to think of truth is developed by Engels in _Anti-Duhring_ , and Lenin in _Materialism and Empiriro-Criticism_, in terms of the dialectic of relative and absolute truth, the concept of objective reality, and their critique of subjective idealism.