There was a time when human life had no order, but like that of animals, was ruled by force: when there was no regard fro the good, nor any punishment for the wicked. And then, I think, men enacted laws (nomoi) for punishment, so that justice (dike) would be ruler (turannos)... and hubris its slave, and whoever did wrong would be punished. Next, since the laws prevented people only from resorting to violence openly, but they continued to do so in secret, then I think for the first time some shrewd and clever (sophos) individual invented fear of the gods for mortals, so that the wicked would have something to fear even if their deeds or words or thoughts were secret. In this way, therefore, he introduced the idea of the divine, saying that there is a divinity, strong with eternal life, who in his mind hears, sees, thinks, and attends to everything with his divine nature (phusis). He will hear everything mortals say and can see everthing they do: and if you silently plot evil, this is not hidden from the gods, for our thoughts are known to them. With such stories as these he introduced the most pleasant of lessons, concealing the truth with a false account. And he claimed that the gods dwelt in that place which would particularly terrify men; for he knew that from there mortals have fears and also benefits for their wretched lives--from the revolving sky above, where he saw there was lightning, the fearful din of thunder and the starry radiance of heaven, a fine embroidery of Time, the skilful (sohos) craftsman. Thence too comes the bright mass of a star, and damp showers are sent down to earth. With fears like these he surrounded me, and using them in his story he settled the divinity in a fitting place, and quenched lawlessness (anomia) by means of laws (nomoi) ... Thus, I think, someone first persuaded mortals to believe (nomizein) there was a race of gods.
Lines from a satyr play
DK 88B25, translated by Davies, 'Sisyphus and the Invention of Religion,' BICS 36 (1989)

Justice (Dikaiosyne) therefore, is not violating the rules (nomima) of the city in which one is a citizen. Thus a person would best observe justice to his own advantage if he paid heed to the laws (nomoi) when in the presence of witnesses, but to the demands of nature (phusis) when not in the presence of witnesses. For the demands of law are adventitious, those of nature inescapable... thus someone who violates the laws avoids shame and punishment if those who have joined in agreement do not observe him, but not if they do. But if someone tries to violate one of the inherent demands of nature, which is impossible, the harm he suffers is no less if he is seen by no one, and no greater if all see him (DK 87B44a)
Fragment of Antiphon's On Truth

In the second half of the 5th century, 'Sophists' arose. They are professional teachers who purported to teach rhetoric and sometimes morality for pay.

Among the biggest names are Gorgias, Protagoras, Hippias, Prodicus. Although they are not from Athens, they all were active and left significant marks at Athens.

Plato criticizes them heavily, although he takes them seriously much of the time.

Protagoras apparently said:
"Man is the measure of all things, of the things that are, that they are, of the things that are not, that they are not."