According to the Lacedæmonian practice, it was necessary first that the Spartans themselves, apart from their allies, should decide whether there existed a sufficient case of wrong done by Athens against themselves or against Peloponnesus—either in violation of the Thirty Years’ Truce, or in any other way. If the determination of Sparta herself were in the negative, the case would never even be submitted to the vote of the allies; but if it were in the affirmative, then the latter would be convoked to deliver their opinion also: and assuming that the majority of votes coincided with the previous decision of Sparta, the entire confederacy stood then pledged to the given line of policy—if the majority was contrary, the Spartans would stand alone, or with such only of the confederates as concurred. Even in the oligarchy of Sparta, such a question as this could only be decided by a general assembly of Spartan citizens, qualified both by age, by regular contribution to the public mess, and by obedience to Spartan discipline. To the assembly so constituted the deputies of the various allied cities addressed themselves, each setting forth his case against Athens. The Corinthians chose to reserve themselves to the last, after the assembly had been inflamed by the previous speakers.
Of this important assembly, on which so much of the future fate of Greece turned, Thucydides has preserved an account unusually copious. First, the speech delivered by the Corinthian envoys. Next, that of some Athenian envoys, who happening to be at the same time in Sparta on some other matters, and being present in the assembly so as to have heard the speeches both of the Corinthians and of the other complainants, obtained permission from the magistrates to address the assembly in their turn. Thirdly, the address of the Spartan king Archidamus, on the course of policy proper to be adopted by Sparta. Lastly, the brief, but eminently characteristic, address of the ephor, Sthenelaidas, on putting the question for decision. These speeches, the composition of Thucydides himself, contain substantially the sentiments of the parties to whom they are ascribed. Neither of them is distinctly a reply to that which has preceded, but each presents the situation of affairs from a different point of view.
To dwell much upon specific allegations of wrong, would not have suited the purpose of the Corinthian envoy; for against such, the Thirty Years’ Truce expressly provided that recourse should be had to amicable arbitration—to which recourse he never once alludes. He knew that, as between Corinth and Athens, war had already begun at Potidæa; and his business, throughout nearly all of a very emphatic speech, is to show that the Peloponnesian confederacy, and especially Sparta, is bound to take instant part in it, not less by prudence than by duty. He employs the most animated language to depict the ambition, the unwearied activity, the personal effort abroad as well as at home, the quick resolves, the sanguine hopes never dashed by failure—of Athens, as contrasted with the cautious, home-keeping, indolent, scrupulous routine of Sparta. He reproaches the Spartans with their backwardness and timidity, in not having repressed the growth of Athens before she reached this formidable height, especially in having allowed her to fortify her city after the retreat of Xerxes and afterwards to build the Long Walls from the city to the sea. The Spartans (he observes) stood alone among all Greeks in the notable system of keeping down an enemy, not by acting, but by delaying to act—not arresting his growth, but putting him down when his force was doubled. Falsely indeed had they acquired the reputation of being sure, when they were in reality merely slow. In resisting Xerxes, as in resisting Athens, they had always been behindhand, disappointing and leaving their friends to ruin; while both these enemies had only failed of complete success through their own mistakes.