History of the Peloponnesian War

For this very empire we gained, not by acting with violence, but through your having been unwilling to stand by them to finish the business with the barbarian, and through the allies having come to us, and of their own accord begged us to become their leaders:

and from this very fact we were compelled at first to advance it to its present height, principally from motives of fear, then of honour also, and afterwards of advantage too.