The Polis, or city-state, according to Aristotle was needed to set the Greeks apart from barbarians. “The proof that the state is a creation of nature and prior to the individual is that the individual, when isolated, is not self-sufficing; and therefore he is like a part in relation to the whole”.  Aristotle delivers the argument that slavery is not only natural among man but that another natural occurrence is the political structures that men create to rule their communities.  Furthermore, Aristotle believed that men could not be truly happy if they went against any of the natural order of things, including political values of the time. 
The middle class was also of importance in Aristotle’s views of a perfect society as he believed they were the best to rule over society. For example, he saw that the very rich could lose sight of the population’s needs because of their lack of needs; and the very poor could be viewed as disgraceful and most likely to become criminal elements within the society.  “Again, the middle class is least likely to shrink from the rule, or to be over-ambitious for it; both of which are injuries to the state”. 
 Aristotle. “Aristotle: The Polis, from Politics.” Internet History Sourcebooks. https://sourcebooks.fordham.edu/ancient/Aristotle-politics-polis.asp
 Edward Clayton, “Aristotle: Politics,” Internet Encyclopedia of Philosophy and its Authors, accessed May 25, 2017, http://www.iep.utm.edu/aris-pol/.
 Aristotle. Aristotle: The Polis, from Politics.