It was upon this same ground probably that the stationary party defended all the prerogatives of the senate of Areopagus—denouncing the curtailments proposed by Ephialtes as impious and guilty innovations. How extreme their resentment became, when these reforms were carried,—and how fierce was the collision of political parties at this moment,—we may judge by the result. The enemies of Ephialtes caused him to be privately assassinated, by the hand of a Bœotian of Tanagra named Aristodicus. Such a crime—rare in the political annals of Athens, for we come to no known instance of it afterwards until the oligarchy of the Four Hundred in 411 B.C.—marks at once the gravity of the change now introduced, the fierceness of the opposition offered, and the unscrupulous character of the conservative party. Cimon was in exile and had no share in the deed. Doubtless the assassination of Ephialtes produced an effect unfavourable in every way to the party who procured it. The popular party in their resentment must have become still more attached to the judicial reforms just assured to them, while the hands of Pericles, the superior leader left behind and now acting singly, must have been materially strengthened.
It is from this point that the administration of that great man may be said to date: he was now the leading adviser (we might almost say Prime Minister) of the Athenian people. His first years were marked by a series of brilliant successes—already mentioned—the acquisition of Megara as an ally, and the victorious war against Corinth and Ægina. But when he proposed the great and valuable improvement of the Long Walls, thus making one city of Athens and Piræus, the same oligarchical party, which had opposed his judicial changes and assassinated Ephialtes, again stood forward in vehement resistance. Finding direct opposition unavailing, they did not scruple to enter into treasonable correspondence with Sparta—invoking the aid of a foreign force for the overthrow of the democracy: so odious had it become in their eyes, since the recent innovations. How serious was the hazard incurred by Athens, near the time of the battle of Tanagra, has been already recounted; together with the rapid and unexpected reconciliation of parties after that battle, principally owing to the generous patriotism of Cimon and his immediate friends. Cimon was restored from ostracism on this occasion, before his full time had expired; while the rivalry between him and Pericles henceforward becomes mitigated, or even converted into a compromise, whereby the internal affairs of the city were left to the one, and the conduct of foreign expeditions to the other. The successes of Athens during the ensuing ten years were more brilliant than ever, and she attained the maximum of her power: which doubtless had a material effect in imparting stability to the democracy as well as to the administration of Pericles—and enabled both the one and the other to stand the shock of those great public reverses, which deprived the Athenians of their dependent landed alliances, in the interval between the defeat of Coronea and the Thirty Years’ Truce.
Along with the important judicial revolution brought about by Pericles, were introduced other changes belonging to the same scheme and system.
Thus a general power of supervision both over the magistrates and over the public assembly, was vested in seven magistrates, now named for the first time, called nomophylaces, or law-guardians, and doubtless changed every year. These nomophylaces sat alongside of the Proedri or presidents both in the senate and in the public assembly, and were charged with the duty of interposing whenever any step was taken or any proposition made contrary to the existing laws: they were also empowered to constrain the magistrates to act according to law.