I am teaching Aeneid 1 for the first time, so please pardon the Newbie question, but in looking at lines 19-20: “Progeniem sed enim Troiano a sanguine duci audierat, Tyrias olim quae verteret arces;” you have the audi[v]erat, secondary tense which would seem to trigger a pluperfect subjunctive, based on my understanding of sequence of tenses, since this is something that would happen after she had heard of Aeneas. Yet you get an imperfect subjunctive. I know it’s indirect discourse, but doesn’t that follow the same sequence of tenses? I look forward to any wisdom y’all have.
https://classics.osu.edu/Undergraduate-Studies/Latin-Program/Grammar/mood/subjunctive/Dependent-subjunctives/sequence-tenses
Best,
Mark Hamilton
After a “secondary” tense you have two options:
If the action described happened in the past/earlier than the main verb, you use the pluperfect subjunctive.
If it happens at the same time or will happen in the future, you use the imperfect subjunctive.
From Juno’s point of view, the “overthrowing” is going to happen in the future (“olim”), so it’s going to happen (long) after the “hearing”, as you have pointed out correctly. This means the imperfect subjunctive should be used, as is the case.
Dear Laurentius Mons:
Awesome, thank you. So the Ohio State University page is incorrect. It says the pluperfect is the time prior and the time after. Very sloppy. Perhaps the reason I’ve always struggled with this is that reputable sources (I consider Ohio State Classics to be very reputable) clearly get this wrong. I’ll always be using the Wheelock’s definition from now on. Thank you again.
Best,
Mark Hamilton
I wrote Ohio State 
.
Dear OSU Classics:
As far as I can tell, your description of sequence of tenses is incorrect on the following website: https://classics.osu.edu/Undergraduate-Studies/Latin-Program/Grammar/mood/subjunctive/Dependent-subjunctives/sequence-tenses
The correct sequence of tenses, for instance, is as follows: for a secondary tense, the subordinate clause following is either imperfect subjunctive for the same time or after the main verb or pluperfect subjunctive for the time before the tense of the main verb.
Consider the famous line from Aeneid 1:20: “audi[v]erat, Tyrias olim quae verteret arces.” This only makes sense considering the above grammatical correction. I only realized this with the help of another Latin student (I should say scholar), but Wheelock’s Chapter 30 confirms it. It would be awesome to change this so that others do not waste any time on this issue. Thank you for your help. Your resources, save this one slight error (the type of which I make all the time), have been extremely helpful.
Best,
Mark Hamilton
In fairness to the Ohio State page it does say that “For most scenarios in Latin, the rules are such:”. I dont think they claim to be exhaustive.
A better treatment of the sequence of tenses can be found here :
http://dcc.dickinson.edu/grammar/latin/sequence-tenses
and the the special rules for the tenses of the subjunctive in dependent clauses follow are here
http://dcc.dickinson.edu/grammar/latin/sequence-tenses
I think that the Allen and Greenough Latin Grammar which has been edited and formatted by Dickinson College is a useful resource. It has a good search function which helps to find the section you might need.
I think what might need some explaining is why duci is present. Austin explains it thus “because the train of events was already in being”.
Verteret seems to be explained as either a subjunctive of characteristic or a relative clause of purpose.
I enjoyed reading Jones’ comment here " When in 29 BC Augustus decided to rebuild Carthage…, the top of the city needed to be flattened to provide the base for the new city. The Romans physically sliced off the top of the hill and shovelled down the hillside over 136,000 cubic yards of earth and rubble, as we can tell from the later material spread down it (the evidence is archaeological). uerteret indeed!"