Diogenes Laertius, Vitae philosophorum 1.110 [Epimenides]
“Epimenides was known among the Greeks and was thought to be extremely beloved to the gods. For this reason, when the Athenians were once afflicted by a plague and the Pythian oracle prophesied that they should cleanse their city, they sent a ship along with Nikias the son of Nikêratos, summoning Epimenides.
He made it to Athens at the time of the 46th Olympiad [c. 596 BCE] and cleansed the city. He stopped it in the following manner. After obtaining white and black sheep, he led them to the Areopagos and then allowed them to go wherever they wanted there. He ordered the people following them to sacrifice the sheep to whichever god was proper to the place where each sheep laid down.
This is how the plague stopped. For this reason it is still even today possible to find altars without names in certain Athenian neighborhoods as a commemoration of that ancient cleansing. Some people report that Epimenides indicated the pollution from the Kylon scandal as the cause of the plague along with a resolution for it. For this reason, they killed two youths, Kratinos and Ktêsibios and the suffering was relieved.”
(110) γνωσθεὶς δὲ παρὰ τοῖς ῞Ελλησι θεοφιλέστατος εἶναι ὑπελήφθη. ὅθεν καὶ Ἀθηναίοις ποτὲ λοιμῶι κατεχομένοις ἔχρησεν ἡ Πυθία καθῆραι τὴν πόλιν, οἱ δὲ πέμπουσι ναῦν τε καὶ Νικίαν τὸν Νικηράτου εἰς Κρήτην, καλοῦντες τὸν Ἐπιμενίδην. καὶ ὃς ἐλθὼν ὀλυμπιάδι τεσσαρακοστῆι ἕκτηι ἐκάθηρεν αὐτῶν τὴν πόλιν, καὶ ἔπαυσε τὸν λοιμὸν τοῦτον τὸν τρόπον· λαβὼν πρόβατα μέλανά τε καὶ λευκά, ἤγαγεν πρὸς τὸν ῎Αρειον πάγον, κἀκεῖθεν εἴασεν ἰέναι οἷ βούλοιντο, προστάξας τοῖς ἀκολούθοις, ἔνθα ἂν κατακλινῆι αὐτῶν ἕκαστον, θύειν τῶι προσήκοντι θεῶι· καὶ οὕτω λῆξαι τὸ κακόν· ὅθεν ἔτι καὶ νῦν ἔστιν εὺρεῖν κατὰ τοὺς δήμους τῶν Ἀθηναίων βωμοὺς ἀνωνύμους, ὑπόμνημα τῆς τότε γενομενης ἐξιλάσεως. οἱ δὲ τὴν αἰτίαν εἰπεῖν τοῦ λοιμοῦ τὸ Κυλώνειον ἄγος σημαίνειν τε τὴν ἀπαλλαγήν· καὶ διὰ τοῦτο ἀποθανεῖν δύο νεανίας Κρατῖνον καὶ Κτησίβιον, καὶ λυθῆναι τὴν συμφοράν