Hence it may be concluded that the happiest state of society is that in which supreme power resides in the whole body of a well-informed people. This is an imaginary, perhaps an unattainable, state of things. Yet, in some measure, we may approximate to it; and he alone deserves the name of a great statesman, whose principle it is to extend the power of the people in proportion to the extent of their knowledge, and to give them every facility for obtaining such a degree of knowledge as may render it safe to trust them with absolute power. In the mean time, it is dangerous to praise or condemn constitutions in the abstract; since, from the despotism of St. Petersburg to the democracy of Washington, there is scarcely a form of government which might not, at least in some hypothetical case, be the best possible.

Therefore a wise prince ought to adopt such a course that his citizens will always in every sort and kind of circumstance have need of the state and of him, and then he will always find them faithful.

Your friend Plato holds that commonwealths will only be happy when either philosophers rule or rulers philosophize: how remote happiness must appear when philosophers won't even deign to share their thoughts with kings.

What pleases the prince has the force of law.
(Quod principi placuit legis habet vigorem.)

Plato argued that in a good society the ratio of the richest to the poorest person's income should be at the most four to one.

Plato is correct about democracy. It is essentially mob rule. And once the mob gets an idea into its collective head, it’s almost impossible to get it out, or modify it in any way. In an era of mass communication and irresponsible media, it can be a deadly characteristic.

What I have here advanced is confirmed by the unanimous testimony of historians, and is extremely agreeable to the nature of things. For it is clear that in a monarchy, where he who commands the execution of the laws generally thinks himself above them, there is less need of virtue than in a popular government, where the person entrusted with the execution of the laws is sensible of his being subject to their direction.

Obedience to the laws was very properly regarded as a principal source of improvement. He admitted that no country could be tranquil or prosperous, where the laws were not generally obeyed; but before they could expect that general obedience, the laws themselves ought to be made equal to all.

We see here that Plato recognizes only one ultimate standard, the interest of the state. Everything that furthers it is good and virtuous and just; everything that threatens it is bad and wicked and unjust. Actions that serve it are moral; actions that endanger it, immoral. In other words, Plato’s moral code is strictly utilitarian; it is a code of collectivist or political utilitarianism. The criterion of morality is the interest of the state. Morality is nothing but political hygiene.

This is the collectivist, the tribal, the totalitarian theory of morality: ‘Good is what is in the interest of my group; or my tribe; or my state.’ It is easy to see what this morality implied for international relations: that the state itself can never be wrong in any of its actions, as long as it is strong; that the state has the right, not only to do violence to its citizens, should that lead to an increase of strength, but also to attack other states, provided it does so without weakening itself. (This inference, the explicit recognition of the amorality of the state, and consequently the defence of moral nihilism in international relations, was drawn by Hegel.)

[T]he prince is not subject to his law, nor to the laws of his predecessors, but well to his own just and reasonable conventions.

When therefore we once begin so to love good men, as not only (according to Plato) to esteem the wise man himself happy, and him who hears his discourses sharer in his felicity, but also to admire and love his habit, gait, look, and very smile, so as to wish ourselves to be that very person, then we may be assured that we have made very good proficiency.

He who becomes a Prince through the favour of the people should always keep on good terms with them; which it is easy for him to do, since all they ask is not to be oppressed

That which the God devoted man may not do for any consideration, is indeed also outwardly forbidden in the Perfect State; but he has already cast it from him in obedience to the Will of God, without regard to any outward prohibition. That which alone this God-devoted man loves and desires to do, is indeed outwardly commanded in this Perfect State; but he has already done it in obedience to the Will of God. If, then, this religious frame of mind is to exist in the State, and yet never to come into collision with it, it is absolutely necessary that the State should at all times keep pace with the development of the religious sense among its Citizens, so that it shall never command anything which True Religion forbids, or forbid anything which she enjoins. In such a state of things, the well-known principle, that we must obey God rather than man, could never come into application; for in that case man would only command what God also commanded, and there would remain to the willing servant only the choice whether he would pay his obedience to the command of human power, or to the Will of God, which he loves before all things else. From this perfect Freedom and superiority which Religion possesses over the State, arises the duty of both to keep themselves absolutely separate, and to cast off all immediate dependence on each other.

Happy the man, of mortals happiest he,
Whose quiet mind from vain desires is free;
Whom neither hopes deceive, nor fears torment,
But lives at peace, within himself content;
In thought, or act, accountable to none
But to himself, and to the gods alone.