Having done an exam on Greek Ethics today, thought I'd pose this question to the forum. Is it plausible that at any point in the fourth or third centuries BC, a group of Greek colonists led by a visionary individual could have seriously attempted to set up a city state that functioned along the lines of the ideal state of Plato's "Republic"? If so, how long would such a state have been able to last before, as I suspect, it fell to a revolution from either the worker or the auxiliary classes?