Ressentiment itself, if it should appear in the noble man, consummates and exhausts itself in an immediate reaction, and therefore does not poison: on the other hand, it fails to appear at all on countless occasions on which it inevitably appears in the weak and impotent.
Nietzsche defines the noble man by his psychological immunity to festering ressentiment, his reactive capacity being immediate and self-consuming rather than chronic and corrosive.
, On the Genealogy of Morals, 1887thesis