In NE 1.7 1098a15, Aristotle claims that "human good turns out to be activity of soul exhibiting virtue, and if there are more than one virtue, in accordance with the best and most complete."
What can't a soul act in accordance with multiple virtues? Is the best and most complete virtue practical wisdom (which is defined in 6.4 chapter 5)?
He doesn't define "best and most complete" in absolute terms, nor in strictly practical ones.
The main point is that there are different ways to approach virtue and our best advise would be to examine things based on the nature (context) of the problem.
What makes me understand what he means is in the 1098b from the Greek translation, but honestly when I read the English one, it seems to me very poor, nearly meaningless.
In NE 1.7 1098a17-18, the passage "if there are more than one virtue, in accordance with the best and most complete" is the Greek singular meaning "the best and most complete virtue".
εἰ δὲ πλείους αἱ ἀρεταί, κατὰ τὴν ἀρίστην καὶ τελειοτάτην
I don't read that as saying that the soul can't act in accordance with more than one virtue, instead I read it as saying that human good in particular is activity of the soul in accordance with the best of them all.
