Aristotle was in fact a Macedonian by birth and had as one of his utmost desires to be accepted in Athens as a full-fledged citizen, something he never attained. To be or not a citizen at those times, was the determinant factor in the importance each one attained in the social structure. One has to keep in mind that all the political concepts that we inherited from the Greeks, got a different perspective at those times, where slavery was normally accepted and practised against the non-Greeks human beings. Aristotle was a disciple of Plato, whom he quotes many times in a derogatory manner, and he lived in Athens many years after years of tutorship of Philip and his son Alexander of Macedonia, to whom he did not mention a word of praise or reprimand in this book. What amazed most after reading this excelent book is the maturity the institutions had attained at his times, and the degree of accuracy and detail to which he devotes many chapters analysing the constitutions of many Greek states, Sparta included. One word of caution has to be addresed to the student of poltics: this is not a book about statecraft or the arts of governing people at 350 BC. All in all, the text seems to lose some strenght due to the impossibity of translating so rich a text and by the lack of precise terms for each and every situation there described. But, in the end, the reader will get a glimpse of this very important period of western civilazation, specially if one has in mind that the heyday of Greece was gone and what lays ahead was the supremacy of Rome as world militar empire. To add interest to the reader, one has to keep in mind that the powerfull influence the aristotelian thought had in the medieval thinking.
Just as in most of his other books, in "The Politics", Aristotle becomes the founder of organized, ordered, and systematic thought. Of course, he was not the first philosopher to think about the organization and governance of societies, but his work is the first classification and comparison of different possible systems. As I said in a recent review of Aristotle's "Nicomachean Ethics", his greatest originality is the stripping off of myth, legend, metaphor and poetics from his exposition of the subject. This is his main difference with his predecessor and teacher, Plato. This makes for a drier reading, but also for a clearer and better organized rendering of his clear thought. It can be said, moreover, that Plato and Aristotle constitute the founding pillars of the two main currents in Western thought: idealism (Plato) vs. realism (Aristotle). Although any tragedies deriving from these sources is, of course, not a responsibility of these great thinkers, it can be said, in general, the following:
The idealist tradition inaugurated by Plato led to the rise of universal, all-encompassing theories. That is, those which assert that there is a single unifying principle tying up together economics, politics, ethics, and social organization, and that this principle (whichever it may be) is suitable for any society at any time and place. Hence, Rousseaunianism, Socialism, Communism.
The "realist" tradition springing from Aristotle simply says that human problems can not be resolved by magical formulas or recipes. Social situations can not be severed from their immediate environment. Aristotle, then, classifies possible types of systems and defines their advantages and disadvantages for different types of societies. His approach, then, is that there can be no universal and general solutions or organizing principles. Aristotle is absolutely practical in his approach, as opposed to the theoretical systems imagined (as opposed to observed) by Plato. Hence: liberalism, Realpolitik, capitalism, democracy (or I should say "capitalisms" and "democracies", since there are very different varieties of these systems). Aristotle examines then distinct kinds of Constitutions, what they require to be effective, and what effects they might bring upon.
Read it, then, for a clear and well-ordered exposition of themes, subthemes, and advice. Here you will find the origin of half of Western political thought. And precisely the half that seems to be winning the race.