I've about reached the end of what I can say about what it means to say that Aristotle does not think there is an art of the good life. Hopefully, yesterday's post made it clear that the important question is whether virtue can in any way be an art (techne), as opposed to some other spiritual activity. We won't get anywhere answering this question completely without a close reading of Book VI of Nicomachean Ethics and probably Book V, too.
For now, I just want to wrap this series up by pointing out that the very question about what spiritual activity constitutes virtue is dependent on Plato's philosophical findings as published in the Republic. Plato could still take it as a reputable opinion (endoxa) that virtue is an art. But he brings this opinion to the point of crisis through his account of justice. Book II , which obliquely introduces justice in the form of a division of labor, shows that art as an activity of the soul is subject to competition, not between artists but within each artist's soul; two arts in the same soul ruin each other. The discovery of this competition makes it impossible to think of virtue as an art.
Although, as we've seen, Aristotle starts his treatise on a dialectical ground of opinions, these probable starting points notably omit the formerly reputable opinion that virtue is an art. In this omission, which makes the inquiry of Book VI possible, Aristotle follows the thinking of Plato.
That is all I mean by "There can therefore be no art concerning the accomplishment of the human good, and that is just what Aristotle thinks." Admittedly, I wanted to mean more by it when I wrote it a few days ago, but perhaps I should say that I wanted to mean less, since I was thinking of an identity in the conclusions, and now I am thinking of an identity in the beginning, and of course the beginning is more than half the whole (as both Plato and Aristotle say).