In the last few pages of the Nicomachean Ethics Aristotle returns to the original question 'What is human happiness?' One expects the end of a long inquiry to glance back towards its starting-point. The moment of ending is also of course the occasion for glancing forward to what might be built on what has been done. And it is the opportunity for final selective emphasis on some theme, perhaps implicit but hardly stated, which the philosopher especially desires to leave fresh in his listeners' minds-- fresh in the sense of alive, but not in the sense of philosophically unmotivated by what goes before, at any rate if we are to take the work as a more or less unified development. And it is only reasonable in the first instance to take the Nicomachean Ethics as that.
As for what sort of inquiry is next in order, Aristotle reflects on this in the final sentences of X.9, in which he closes the NE with a call for work in political science.
Now our predecessors have left the subject of legislation to us unexamined; it is perhaps best, therefore, that we should ourselves study it, and in general study the question of the constitution, in order to complete to the best of our ability that philosophy of human nature. First, then, if anything has been said well in detail by earlier thinkers, let us try to review it; then in the light of the constitutions we have collected let us study what sorts of influence preserve and destroy states, and what sorts preserve or destroy the particular kinds of constitution, and to what causes it is due that some are well and others ill administered. When these have been studied we shall perhaps be more likely to see which constitution is best, and how each must be ordered, and what laws and customs it must use. Let us make a beginning of our discussion (1181 b 12-23)
In fact, the transition indicated by the last sentence has already begun. Aristotle has just been spelling out some proposals for moral education which cannot be effective except by public action through legislation. For this reason he will now undertake a thorough study of legislation and political institutions in general. Is it then