History of the Peloponnesian War

First of all, therefore, came in the Mantineans and their confederates, which they did for fear of the Lacedaemonians. For a part of Arcadia, during the war of Athens, was come under the obedience of the Mantineans, over which they thought the Lacedaemonians, now they were at rest, would not permit them any longer to command; and therefore they willingly joined with the Argives, as being, they thought, a great city, ever enemy to the Lacedaemonians, and governed as their own by democracy.

When the Mantineans had revolted, the rest of Peloponnesus began also to mutter amongst themselves that it was fit for them to do the like; conceiving that there was somewhat in it more than they knew that made the Mantineans to turn; and were also angry with the Lacedaemonians, amongst many other causes, for that it was written in the articles of the Attic peace that it should be lawful to add unto or take away from the same, whatsoever should seem good to the two cities of the Lacedaemonians and the Athenians.

For this was the article that the most troubled the Peloponnesians and put them into a jealousy that the Lacedaemonians might have a purpose, joining with the Athenians, to bring them into subjection; for in justice, the power of changing the articles ought to have been ascribed to all the confederates in general.