Eudemian Ethics II 6 is meant to introduce Aristotle's discussion of voluntary action in II 7–9. The majority of II 6, however, consists of a somewhat obscure discussion of the ways in which humans, alone among animals, are origins of action (ἀρχαὶ πράξεων). It is not at all clear how that topic is meant to relate to the topic of voluntary action until the following passage, towards the end of the chapter, in which Aristotle relates being the cause (αἴτιος) and origin of action to praiseworthiness and blameworthiness and to the voluntary (1223a9–16):
ἐπεὶ δ’ ἥ τε ἀρετὴ καὶ ἡ κακία καὶ τὰ ἀπ’
αὐτῶν ἔργα τὰ μὲν ἐπαινετὰ τὰ δὲ ψεκτά (ψέγεται γὰρ (10)
καὶ ἐπαινεῖται οὐ διὰ τὰ ἐξ ἀνάγκης ἢ τύχης ἢ φύσεως
ὑπάρχοντα, ἀλλ’ ὅσων αὐτοὶ αἴτιοι ἐσμέν· ὅσων γὰρ ἄλλος
αἴτιος, ἐκεῖνος καὶ τὸν ψόγον καὶ τὸν ἔπαινον ἔχει), δῆλον
ὅτι καὶ ἡ ἀρετὴ καὶ ἡ κακία περὶ ταῦτ’ ἐστιν ὧν αὐτὸς
αἴτιος καὶ ἀρχὴ πράξεων. ληπτέον ἄρα ποίων αὐτὸς αἴτιος (15)
καὶ ἀρχὴ πράξεων.
Now, since virtue and vice and the works that come from them are praiseworthy and blameworthy respectively (for one is not blamed or praised for what obtains on account of necessity or chance or nature but for the things we are ourselves causes of; for where someone else is the cause, he bears both the blame and the praise), it is clear that virtue and vice are concerned with what one is oneself a cause of and starting point of action.