One of the arguements Plato uses against democracy.
Ruling, he sez, is a craft just like any other, in that those trained in it will do much better than those who are not.
In a democracy, "everyone" can vote on how to run things. This is as silly as letting everyone vote on what to do about your cardiac arrest or a broken carborator. These things are better left to the experts, not the rabble.
Plato believed that the ones best suited to rule would have 50 years of training: 30 years of basics, like literacy, music, mathmatics, military training, and physical training. Then 5 years of philosophy, 15 of military service, and viola!, you're fit to rule. The philosophy is of crucial importance; if you spend enough time meditating on the forms, you will recognize "good" when you see it.
Of course, because these people will be smart, they will be able to think of better things to do than rule over a buch of unruly humans. But they will be enlightened, and see it as their unhappy duty.
To make sure that they do not enjoy it too much, they would not be allowed any private property.
Aristocracy rules.