Nemesis, daughter of Nyx in Hesiod, punished hubris and corrected excessive fortune; her name comes from nemein, to apportion, to give what is due. Her great sanctuary stood at Rhamnous in Attica. Ovid gives her the perfect case: a spurned suitor of Narcissus prays to her, and she leads the youth to the pool where he falls in love with a love that cannot love back. Pindar uses nemesis as a common noun for righteous anger at the overclaim.
Athenians prayed to Nemesis after triumphs, not after crimes, to avert divine envy, phthonos, and restore balance. The Greeks genuinely believed too much luck was cosmically unstable: the wheel turns, the scales must level, and the correction arrives with the patience of mathematics. Modern usage shrank her to the rival you cannot beat, keeping only the inevitability and losing the bookkeeping.
The claim: the deepest modern survival of the goddess is structural, the enemy whose existence your own choices created, Shadow of Mordor's Nemesis System, where wounded orcs return promoted, is her exact mechanism: consequence accrues, strengthens, returns. Verdict: Jung's enantiodromia, extremes flip into opposites, is the same law in clinical dress. The goddess is gone; the ledger is load-bearing. Hubris still clears its own account.
If the universe keeps books, who taught it double-entry?