The modern self as we understand it today was unknown to the ancient Greeks. For Plato, as with all his fellow Athenians, individuals were defined by the role they played in the wider community. In political terms, this meant that citizens of the Athenian polis were inextricably linked to the state; there was no real separation between the two. For free male citizens of Athens, there were numerous opportunities for involvement in this direct democracy. It was a citizen jury, for example, that presided over the trial and sentencing of Plato's mentor, Socrates.
In his own ideal state, Plato takes the identity of citizen and state a step further. In modern terms, Plato's utopia can seem disturbingly similar to a totalitarian system. However, such an assessment would be anachronistic. Plato is concerned with human freedom, but his conception of freedom is out of step with more modern notions.
As far as Plato is concerned, the state can only function properly if every group in society carries out its proper role, analogous to the proper functioning of the human soul. The state, like the soul, is divided into three parts: reason, spirit, and appetite. Reason is associated with Plato's philosopher-kings, the future rulers of his ideal state; spirit is the dominant characteristic of the warrior class; appetite distinguishes the mass of the population.
True freedom in this polity resides in aristocratic freedom, the rule of reason unimpeded by desires. At this point, we need to bear in mind Plato's metaphysics, which form the basis of his political thought. According to Plato, if the appetitive part of the soul is allowed to predominate, then we will become slaves to our passions, appetites, and desires. It is the same with the ideal state. Plato was strongly critical of the Athenian system of democracy, which had, after all, been responsible for putting his venerated mentor to death. As such, he was keen to ensure that in his utopia, the masses—the appetitive element in the state—should not be allowed to exercise ultimate political power. Otherwise, Plato believed, true freedom, the rule of reason, would be destroyed and replaced by a system based upon the unfettered exercise of the baser human wants and desires.