How did Friedrich Nietzsche trace the shift from “good and bad” to “good and evil”?

Friedrich Nietzsche traced the shift from "good and bad" to "good and evil" through a genealogical analysis of moral language, specifically examining the etymology of the German terms gut ("good"), schlecht ("bad"), and böse ("evil").1

Originally, the distinction between "good" and "bad" was descriptive and nonmoral. It served as a reference to social status: the "good" were the privileged masters, while the "bad" were the base or common people.1

The transition to a "good and evil" contrast occurred when those in the "slave" position sought vengeance against the masters. By converting the attributes of mastery into vices, they inverted the original values. Traits such as pride, competition, and autonomy were rebranded as sinful, while qualities like meekness, humility, and obedience were elevated to virtues. This "slave morality" claimed absolute authority, fundamentally altering the landscape of Western ethics by framing the powerful as "evil" and the weak as "good". Nietzsche viewed this development as a symptom of a declining life, characterizing it as an expression of the ascetic ideal.1