We must hold very much the same opinion about the Athenian constitution.
For <a class="linkToPlace" target="_blank" href="/place?placename=Athens&groupId=379&placeId=715">Athens</a> also, though she perhaps enjoyed more frequent periods of success, after her most glorious one of all which was coeval with the excellent administration of Themistocles, rapidly experienced a complete reverse of fortune owing to the inconstancy of her nature.
For the Athenian populace always more or less resembles a ship without a commander.
In such a ship when fear of the billows or the danger of a storm induces the mariners to be sensible and attend to the orders of the skipper, they do their duty admirably.
But when they grow over-confident and begin to entertain contempt for their superiors and to quarrel with each other, as they are no longer all of the same way of thinking, then with some of them determined to continue the voyage, and others putting pressure on the skipper to anchor, with some letting out the sheets and others preventing them and ordering the sails to be taken it, not only does the spectacle strike anyone who watches it as disgraceful owing to their disagreement and contention, but the position of affairs is a source of actual danger to the rest of those on board;
so that often after escaping from the perils of the widest seas and fiercest storms they are shipwrecked in harbour and when close to the shore.
This is what has more than once befallen the Athenian state. After having averted the greatest and most terrible dangers owing to the high qualities of the people and their leaders, it has come to grief at times by sheer heedlessness and unreasonableness in seasons of unclouded tranquillity.
Therefore I need say no more about this constitution or that of Thebes, states in which everything is managed by the uncurbed impulse of a mob in the one case exceptionally headstrong and ill-tempered and in the other brought up in an atmosphere of violence and passion.
Walbank Commentary