You know and we know, as practical men that the question of justice arises only between parties equal in strength and that the strong do what they ca… - Thucydides

Right, as the world goes, is only in question between equals in power, while the strong do what they can and the weak suffer what they must.

Civil war brought many hardships to the cities, such as happen and will always happen as long as human nature is the same, although they may be more or less violent or take different forms, depending on the circumstances in each case.

This expedition of the Athenians led to the first open quarrel between them and the Lacedaemonians. For the Lacedaemonians, not succeeding in storming the place, took alarm at the bold and original spirit of the Athenians. They reflected that they were aliens in race, and fearing that, if they were allowed to remain, they might be tempted by the Helots in Ithomè to change sides, they dismissed them, while they retained the other allies. But they concealed their mistrust, and merely said that they no longer needed their services.

(Book 1 Chapter 102.3)

we do not say that a man who takes no interest in politics is a man who minds his own business; we say that he has no business here at all.