History of the Peloponnesian War

To the question why they broke the treaty, I answer by placing first an account of their grounds of complaint and points of difference, that no one may ever have to ask the immediate cause which plunged the Hellenes into a war of such magnitude.

The real cause I consider to be the one which was formally most kept out of sight. The growth of the power of Athens, and the alarm which this inspired in Lacedaemon, made war inevitable. Still it is well to give the grounds alleged by either side, which led to the dissolution of the treaty and the breaking out of the war.