Hesiod, Erga kai hēmerai, 11-26

οὐκ ἄρα μοῦνον ἔην Ἐρίδων γένος, ἀλλ’ ἐπὶ γαῖαν
εἰσὶ δύω· τὴν μέν κεν ἐπαινέσσειε νοήσας,
ἣ δ’ ἐπιμωμητή· διὰ δ’ ἄνδιχα θυμὸν ἔχουσιν.
ἣ μὲν γὰρ πόλεμόν τε κακὸν καὶ δῆριν ὀφέλλει,
σχετλίη· οὔ τις τήν γε φιλεῖ βροτός, ἀλλ’ ὑπ’ ἀνάγκης
ἀθανάτων βουλῇσιν Ἔριν τιμῶσι βαρεῖαν.
τὴν δ’ ἑτέρην προτέρην μὲν ἐγείνατο Νὺξ ἐρεβεννή,
θῆκε δέ μιν Κρονίδης ὑψίζυγος, αἰθέρι ναίων,
γαίης ἐν ῥίζῃσι, καὶ ἀνδράσι πολλὸν ἀμείνω·
ἥ τε καὶ ἀπάλαμόν περ ὁμῶς ἐπὶ ἔργον ἔγειρεν.
εἰς ἕτερον γάρ τίς τε ἰδὼν ἔργοιο χατίζει
πλούσιον, ὃς σπεύδει μὲν ἀρώμεναι ἠδὲ φυτεύειν
οἶκόν τ’ εὖ θέσθαι· ζηλοῖ δέ τε γείτονα γείτων
εἰς ἄφενος σπεύδοντ’· ἀγαθὴ δ’ Ἔρις ἥδε βροτοῖσιν.
καὶ κεραμεὺς κεραμεῖ κοτέει καὶ τέκτονι τέκτων,
καὶ πτωχὸς πτωχῷ φθονέει καὶ ἀοιδὸς ἀοιδῷ.

There was not one kind of Rivalry after all, but two
upon the earth: one you would praise if you knew her well,
but the other is blameworthy, and they differ in character.
For one abets evil war and battle,
wicked: her no man likes, but by necessity,
by the will of the gods, they honor grave Rivalry.
The other was first born of dark Night,
and high-throned Kronidēs, dwelling in the sky,
put her in the roots of the earth, and much better for men.
She incites even the idle to work.
For a man hastens to work when he sees another man
wealthy, who takes care to plow and plant
and set his house in order. Neighbor strives against neighbor
in pursuit of wealth: and this is the Rivalry that is good for man.
And potter rivals potter, and carpenter carpenter,
and beggar envies beggar, and singer singer.