What is the criterion for distinguishing between the excellence of the excellent constitution κατ’ εὐχήν in Politics VII and the excellence of the other excellent constitutions ? Every constitution includes in its composition necessity and good. Yet, unlike what happens in the other excellent constitutions, in the best constitution of Politics VII there is a convergence, not an opposition, between necessity and goodness. This point is confirmed by a change in the meaning of the word ἀναγκαῖον (1328b13-14). In the constitution delineated in Book VII, ultimately matter and form are identical. Both the convergence between necessity and good and the fact that every citizen should be a good man or a ‘maker of virtue’ lead to equate the excellent constitution with the completed form of political capacity. Hence, the relationship between πολιτεία and ἀρίστη πολιτεία is similar to the relationship between ἔργον κιθαριστοῦ and ἔργον σπουδαίου κιθαριστοῦ.