In the previous chapter, you learned that present and imperfect subjunctives are formed in familiar ways, using regular endings, with just small shifts that make them recognizable from their indicative forms. The same idea continues to hold true for the perfect and pluperfect subjunctive forms.
You (hopefully!) remember that in the perfect system you use the 3rd principal part for active verbs and the 4thprincipal part for passive verb forms. The same rules continue in the subjunctive.
Thus, for perfect active subjunctive verbs, you take the 3rd principal part and add the following endings: -erim, -eris, -erit, -erimus, eritis, erint.
You might have noticed that many of these perfect subjunctive forms are identical to future perfect indicative forms—yup! They overlap! It’s okay—you’ll usually be able to figure out the mood from its use within the context of the sentence.
The pluperfect active subjunctive is formed in a similar way as the perfect. Here, you take the 3rd principal part and add the following endings: -issem, -isses, -isset, -issemus, -issetis, -issent.
In the passive voice, the perfect and pluperfect subjunctives use the 4th principal part plus the subjunctive forms of sum, esse, fui. The perfect uses sum in the present subjunctive; the pluperfect uses the imperfect subjunctive forms as seen below. Remember that the 4th principal part is an adjective and will change gender/number according to its subject.
In general, you are less likely to encounter the perfect and pluperfect subjunctive as you read Latin texts. Verbs in these two tenses sometimes appear as a main verb in wishes and potential main clauses. And in upcoming chapters, you may also see them in some conditionals, indirect questions, and temporal clauses.
Usually Latin uses the subjunctive mood in secondary clauses. But sometimes it occurs as the main verb in instances where things may be hypothetical, doubtful, or unreal; basically, stuff that might or might not happen. There are four categories of main verb subjunctive that use different clues or markers that help you interpret the way it is being used in a given context. The table below explains the differences between the uses and provides some examples of each use.
As always, as the translator you get to play a significant role in determining which main verb subjunctive translation makes most sense in a given context. Notice how the only difference between "domum eat!" and "domum eat?" or even "domum eat." is the punctuation? Romans didn't use exclamation points or question marks--when you see those punctuation marks in a text, that's because a modern editor is trying to help you make a decision about how to translate it.