From: P&G
Message: 21258
Date: 2003-04-25
> The [Latin] imperfect subjunctive does have tense reference: It replacesthe
> subjunctive in case the general setting (as, the main clause) is in a pastPrecisely the opposite. In the constructions you are referring to, it
> tense form. So it makes perfect sense to explain it as a past-tense form
> created to fit a pre-existing subjunctive type.