Chris Engelsma wrote:Sorry for all my morphological questions...
First, I look up επιστραφεις in Mounce's Morphology book (MBG) and he lists εστρεψα as the aorist principal part. This implies that it is
first aorist. Yet, επιστραφεις is clearly
second aorist. I guess maybe the addition of the preposition caused this.
Second, being as how επιστραφεις is aorist, I can't figure out what happened to the augment.
Mounce says (BBG 21.20 3rd edition) that the final vowel of the preposition will elide when the augment comes in. He also notes that in a few cases (such as compounds with περι), the final vowel of the prep will stay, and it will contract with the augment. But that doesn't seem to apply to επιστραφεις.
So....there I am. Stuck again.

I question the usefulness of a book like Mounce's Morphology; my stance as a long-time teacher of Greek is that students need to learn in full the conjugation of
all regular verbs and to learn the principal parts of
all (not just two dozen or so) irregular verbs.
In the case of this verb there are two difficulties that seem inherent even in the traditional lexicology: one is the convention of regarding the 1 sg. indic. active as the Lemma from which all other forms are derived,
with the added assumption that compounds based on the verb-root should also be understood in terms of the 1 sg. indic. active as the Lemma; closely related to this is the difficulty/problem that στρέφω and στρέφομαι are entered as a single verb when there's a significant difference between the active and the middle forms based on the root ΣΤΡΕΦ/ΣΤΡΟΦ/ΣΤΡΑΦ. To be sure, there's a basic shared notion of "turning" in all forms derived from the root. But one needs to understand that στρέφω (active) means "cause to turn" while στρέφομαι (middle) is the intransitive verb of bodily motion, "turn." I think that the compounds from this root are more often middle than active (I haven't checked the numbers). Certainly the verb in question here, ἐπιστρέφομαι, is indeed fundamentally a middle verb -- here intransitive -- meaning something like "shift one's direction." If one were learning the principal parts here, I'd say one should learn: Present ἐπιστρέφομαι, Future ἐπιστρέψομαι, Aorist ἐπεστράφην.
Second, being as how επιστραφεις is aorist, I can't figure out what happened to the augment.
There is in fact no augment on ἐπιστραφείς because the form is an aorist nom. sg. m. participle (middle-passive). Only indicatives take an augment. The aorist indicative 1 sg. clearly shows the augment between the elided ending of the prefix and the verb-stem itself: ἐπ-ε-στράφην.
I think that questions like this will continue to arise until some glorious day that ancient Greek pedagogy has taken some forward steps. Learning the ancient Greek verb is hard enough with the best of resources and teachers. In many ways the traditional pedagogical methods and the available resources for learning the verbs are far from being as helpful to students as they could be.