@MJA,
If you read the Declaration of Independence, you will see that in talking of forms of government, Jefferson expresses a perfect understanding of forms Suffering only from metaphysics... And it is one I agree with... It was the church that bought into Plato; mostly because they did not have access to Aristotle until later, and then they preferred him...Until that time, the republic helped them to organize and justify their own sterile society...
It could be that the Republic came closest to its example in the meritocracy of the church, but that history taught what nonsense it really was, that it did not produce a better individual or a more virtuous society...The human understanding of mankind had progress very far by the time of jefferson; and those people, our founding fathers had the example of failed civilizations like Greece and Rome, and also of working Democracies like the Iroquois Confederacy... Why those who wrote the constitution made it so much like Rome on the point of failure I will never know, unless it was that they rather admired the riches and power of the place, and wanted to relive that moment in time...