Nietzsche spells this point out in the case of punishment. The act of
punishing has always been the same, but the meaning of that act has changed
radically. The barbarians of ancient time had very different wills than the
modern slave morality endorses. As a result, though the act of punishing and
the word "punishment" have remained unchanged, they have been interpreted very
differently. Nietzsche is showing that what is significant to us about
punishment is not the act itself, but the meaning that we attach to it. Because
this meaning is independent of and inessential to the act itself, we could
potentially come to understand punishment as meaning pretty much anything.
Because conventional wisdom sees the world in terms of things and deeds rather
than forces and wills, we are unable to separate the meanings of punishment from
the deed itself, and assume that the deed has always had the same meaning.
Nietzsche raises the same point with pretty much all our moral concepts, showing
that, while the words "good," "conscience," "guilt," or "justice" have been
around for a long time, they have, unnoticed by us, taken on very different
meanings depending on the wills that were interpreting them.
