Lycurgus (28.1-28.2)

Now in all this there is no trace of injustice or arrogance, which some attribute to the laws of Lycurgus, declaring them efficacious in producing valour, but defective in producing righteousness. The so-called krupteia, or secret service, of the Spartans, if this be really one of the institutions of Lycurgus, as Aristotle says it was, may have given Plato also[*] this opinion of the man and his civil polity.

This secret service was of the following nature. The magistrates from time to time sent out into the country at large the most discreet of the young warriors, equipped only with daggers and such supplies as were necessary. In the day time they scattered into obscure and out of the way places, where they hid themselves and lay quiet; but in the night they came down into the highways and killed every Helot whom they caught.