I’m on Chapter 13 of H&Q, and this mixed-vs.-root aorist business raises couple of questions in my mind. Δίδωμι and τίθημι both have mixed aorist, but the intransitive aorist of ἵστημι is a root aorist. What of the transitive? Is it mixed or pure first aorist? For example, would the third-person plural transitive aorist indicative active be έστησαν or έστασαν?
Is it a safe assumption to make that any (or almost any) athematic verb with a first aorist form as its third principal part has a mixed aorist?
Finally, the substitution of the stem ἵστε- for the expected ἵστα- in the subjunctive: is that an irregularity unique to ἵστημι or is it generalizable to all athematic verbs whose short-vowel grades have alphas?
ἵστημι set: trans. στήσω shall set, 1 aor. ἔστησα set, ἐστάθην was set, ἵσταμαι set for myself, στήσομαι, ἐστησάμην. Four active tenses are intrans.: 2 aor. ἔστην (set myself) stood, pf. ἕστηκα (have set myself) stand, am standing, εἱστήκη stood, was standing, 2 perf. ἕστατον stand, fut. pf. ἑστήξω shall stand. So also ἵσταμαι set myself, stand, στήσομαι.
N.—The same distinction prevails in the compounds: ἀνίστημι raise up, ἀνέστην stood up, ἀφίστημι set off, cause to revolt, ἀπέστην stood off, revolted, ἀφέστηκα am distant, am in revolt; ἐφίστημι set over, ἐπέστην set myself over, ἐφέστηκα am set over; καθίστημι set down, establish, κατέστην established myself, became established, καθέστηκα am established. The aorist middle has a different meaning: κατεστήσατο established for himself; συνίστημι introduce, unite, συνέστημεν banded together.
According to LSJ, 3rd pl. of either should be ἔ-στη-σαν, but it seems that ἔ-στᾰ-σαν did exist in Epic,
(distinguished from that of the 2nd aor. ἔ-στα-ν) from which in late prose we see ἔ-στᾰ-σα, -σε, etc.
δίδωμι, τίθημι and ἵημι have mixed aorist, in which the plural have a short vowel. (well, not quite; εἱ- instead of ἡ- for ἵημι). ἵστημι does not.
Subjunctives & optatives of -μι verbs are declined like -ω ones, and follow somewhat different
contraction rules with the short-vowel of the stems. The stem of ἵστημι is στα-, never στε-:
σι-στα-* > ἱ-στα-, which is then turned to ἱ-στη- in ind. act. sg.