“All things are subject to interpretation; whichever interpretation prevails at a given time is a function of power and not the truth.” Did Nietzsche really say this? Not quite. Popular culture has slightly misquoted. Instead, the philosopher said:

The correct quote comes from, “Notes (1888),” translated in The Portable Nietzsche (edited by Walter Kaufmann). The quote in full context is as follows.

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That the value of an act should depend on what preceded it in consciousness-how false that is! And yet morality has been measured that way, even criminality.

The value of an act must be measured by its consequences, the utilitarians say: measuring it by its origin implies an impossibility, namely, knowing the origin.

But does one know the consequences? Perhaps as far as five steps. Who could say what an act stimulates, excites, provokes against itself? As a stimulus? Perhaps as the ignition spark for an explosive? The utilitarians are naive. And in the end we would first have to know what is useful: here too their vision extends for only five steps. They have no conception of any great economy which does not know how to dispense with evil.

…

Against that positivism which stops before phenomena, saying “there are only facts,” I should say: no, it is precisely facts that do not exist, only interpretations.

– Nietzsche, 1954 [1888]: 457-458.