How could Aristotle defend the self-sufficiency of political life while claiming the superiority of contemplative life?

In Nicomachean Ethics X.7, Aristotle argues that perfect happiness consists in contemplation alone. The question that I want to take up in this essay is whether the superiority of contemplative life fits with Aristotle’s argument for the self-sufficiency of the political life, according to which politics can lead us to happiness without being guided by philosophical knowledge of the highest sort. My basic argument is that, paradoxical as it may seem, Aristotle is led to acknowledge that contemplative life is superior to political life by the same strand of argumentation which makes him plea for the self-sufficiency of the political life in the first place. In order to show how this argument unfolds, I take my point of departure from Aristotle’s analysis of phronēsis as stated in Nicomachean Ethics VI and bring it to bear on his discussion of the respective virtues of the contemplative and political ways of life in Politics VII.