Friedrich Nietzsche, answered from the texts and cited to the page.
Ressentiment (reactive resentment) begins not as an emotion but as a creative act — or rather, as the substitute for one. When a nature lacks the power to discharge its reactions outwardly, in deeds, those reactions turn inward and ferment. The slave cannot strike his enemy; so he imagines a revenge, and from that imaginary revenge he builds his values.1
The structural point is this: noble valuation begins with a triumphant Yes to itself — "we good ones, we beautiful, happy ones" — and only afterwards, as a pale afterthought, generates the concept "bad" to name what it is not. Ressentiment, by contrast, begins with No.2 It needs an enemy before it can define itself; it requires a hostile external world as the condition of its own existence; physiologically speaking, it cannot act at all without an external stimulus — its action is fundamentally reaction.3
What distinguishes the noble nature is precisely the incapacity to hold a grudge for long. Strong, full natures possess an excess of the power to form, to mold, to recuperate, and to forget — Mirabeau is the example I give: he could not forgive insults simply because he forgot them. Ressentiment, by contrast, is defined by the inability to forget.4
The man of ressentiment squints; his spirit loves hiding places and back doors; he knows how to wait, how to be provisionally self-deprecating, how to keep silent.5 From this enforced patience he draws a compensation the noble man never needs: cleverness, honored as a condition of survival rather than as a luxury.6 The crowning move is the inversion.
The man of ressentiment first conceives "the evil enemy" — that is his deed, his act of creation — and only then, as a pendant, a contrasting shade, does he produce "the good one": himself.7 Noble morality names "bad" what falls below its own standard; slave morality names "evil" what threatens it from outside, and that evil is precisely the noble man himself, seen through a venomous eye, dyed in another color.8
Politically, the pattern persists wherever the underprivileged organize their suffering into a demand. The socialist crying for justice, the Christian condemning the world — both are invalids who feel better for crying out, for whom defamation is a relief.9 The cult of altruism, the hatred of egoism whether one's own or another's, is ressentiment wearing the costume of moral seriousness — self-preservation of the suffering type, not the love of mankind it advertises.10
The slave revolt in morality begins when ressentiment itself becomes creative and gives birth to values: the ressentiment of natures that are denied the true reaction, that of deeds, and compensate themselves with an imaginary revenge.On the Genealogy of Morals, pp. 44–45
While every noble morality develops from a triumphant affirmation of itself, slave morality from the outset says No to what is 'outside,' what is 'different,' what is 'not itself'; and this No is its creative deed.On the Genealogy of Morals, pp. 44–45
in order to exist, slave morality always first needs a hostile external world; it needs, physiologically speaking, external stimuli in order to act at all—its action is fundamentally reaction.On the Genealogy of Morals, pp. 44–45
To be incapable of taking one's enemies, one's accidents, even one's misdeeds seriously for very long—that is the sign of strong, full natures in whom there is an excess of the power to form, to mold, to recuperate and to forget (a good example of this in modern times is Mirabeau, who had no memory for insults and vile actions done him and was unable to forgive simply because he— forgot).On the Genealogy of Morals, pp. 46–47
His soul squints; his spirit loves hiding places, secret paths and back doors, everything covert entices him as his world, his security, his refreshment; he understands how to keep silent, how not to forget, how to wait, how to be provisionally self-deprecating and humble.On the Genealogy of Morals, pp. 46–47
a race of such men of ressentiment is bound to become eventually cleverer than any noble race; it will also honor cleverness to a far greater degree: namely, as a condition of existence of the first importance.On the Genealogy of Morals, pp. 46–47
he has conceived 'the evil enemy,' 'the Evil One,' and this in fact is his basic form and concept, which he then evolves, as an afterthought pendant, a 'good one'—himself!On the Genealogy of Morals, pp. 46–47
this 'bad' of noble origin and that 'evil' out of the cauldron of unsatisfied hatred—the former an after-production, a side issue, a contrasting shade, the latter on the contrary the original thing, the beginning, the distinctive deed in the conception of a slave morality.On the Genealogy of Morals, pp. 48–49
The same applies to the Christian: he condemns, disparages, curses the 'world'—himself not excluded. But that is no reason for taking his clamor seriously. In both cases we are in the presence of invalids who feel better for crying out, for whom defamation is a relief.The Will to Power, pp. 202–203
Hatred of egoism, whether it be one's own (as with Christians) or another's (as with socialists), is thus revealed as a value judgment under the predominating influence of revenge; on the other hand, as an act of prudence for the self-preservation of the suffering.The Will to Power, pp. 202–203