We must not disguise from ourselves that we go to found a city among strangers and enemies, and he who undertakes such an enterprise should be prepar… - Thucydides

There were other and worse forms of lawlessness which the plague introduced at Athens. Men who had hitherto concealed what they took pleasure in, now grew bolder.For, seeing the sudden change, — how the rich died in a moment, and those who had nothing immediately inherited their property, — they reflected that life and riches were alike transitory, and they resolved to enjoy themselves while they could, and to think only of pleasure.

Who would be willing to sacrifice himself to the law of honour when he knew not whether he would ever live to be held in honour? The pleasure of the moment and any sort of thing which conduced to it took the place both of honour and of expediency.

No fear of Gods or law of man deterred a criminal. Those who saw all perishing alike, thought that the worship or neglect of the Gods made no difference.For offences against human law no punishment was to be feared; no one would live long enough to be called to account. Already a far heavier sentence had been passed and was hanging over a man's head; before that fell, why should he not take a little pleasure?

(Book 2 Chapter 53)

To feel pity, to be carried away by the pleasure of hearing a clever argument, to listen to the claims of decency are three things that are entirely against the interests of an imperial power.

(Corinthian:) [B]e not afraid of the immediate danger, but fix your thoughts on the durable peace which will follow. For by war peace is assured, but to remain at peace when you should be going to war may be often very dangerous.

(Book 1 Chapter 124.2)