Nemesis, the daughter of Nyx, represents that power which adjusts the balance of human affairs, by awarding to each individual the fate which his actions deserve.
She rewards, humble, unacknowledged merit, punishes crime, deprives the worthless of undeserved good fortune, humiliates the proud and overbearing, and visits all evil on the wrong-doer; thus maintaining that proper balance of things, which the Greeks recognized as a necessary condition of all civilized life. But though Nemesis, in her original character, was the distributor of rewards as well as punishments, the world was so full of sin, that she found but little occupation in her first capacity, and hence became finally regarded as the avenging goddess only. We have seen a striking instance of the manner in which this divinity punishes the proud and arrogant in the history of Niobe.
Apollo and Artemis were merely the instruments for avenging the insult offered to their mother; but it was Nemesis who prompted the deed, and presided over its execution. Homer makes no mention of Nemesis; it is therefore evident that she was a conception of later times, when higher views of morality had obtained among the Greek nation.
Nemesis is represented as a beautiful woman of thoughtful and benign aspect and regal bearing; a diadem crowns her majestic brow, and she bears in her hand a rudder, balance, and cubit;--fitting emblems of the manner in which she guides, weighs, and measures all human events. She is also sometimes seen with a wheel, to symbolize the rapidity with which she executes justice.
As the avenger of evil she appears winged, bearing in her hand either a scourge or a sword, and seated in a chariot drawn by griffins. Nemesis is frequently called Adrastia, and also Rhamnusia, from Rhamnus in Attica, the chief seat of her worship, which contained a celebrated statue of the goddess.
Nemesis was worshipped by the Romans, (who invoked her on the Capitol), as a divinity who possessed the power of averting the pernicious consequences of envy.
From: Berens, E.M. The Myths and Legends of Ancient Greece and Rome. New York: Maynard, Merril, & Co., 1880. Text in the public domain.