Which are the highest then. Or there are only 2 of them?
He believes Democracy is just a brief transition phase to Tyranny.
The highest is an aristocracy run by philosopher kings who rule by reason and wisdom and dedicate their lives to this and are not allowed to own property.
Or do you mean that Plato was possessed of a higher intelligence than puny mortals like us could hope to properly contemplate, possibly even incapable of error, and therefore we should defer to his musings without using our critical thinking to apply the benefit of 2,360 years of hindsight?
[1] http://en.wikipedia.org/wiki/Plato's_five_regimes
* Just kidding.
2. Timocracy
3. Oligarchy
4. Democracy
5. Tyranny