This etymology, like most of Plato's etymologies in the Cratylus, is never repeated and not found afterwards in Greek scholarly literature. As usual in Plato's Cratylus, the word is parsed as a compound of the adverb ἀεί and the verb "to flow" (this is the Heraclitean theory of mobility), which then undergoes a strong abridgment. The sentence ἴσως δὲ αἱρετὴν λέγει, ὡς οὔσης ταύτης τῆς ἕξεως αἱρετωτάτης, kept by Burnet in his edition, is not by Plato, it is a comment inserted into the text and trying to bring Plato's weird etymology back to one of the standard ones, namely, the one deriving it from αἱρετός (see ἀρετή / αἱρέω).