2. By the Sequence of Tenses Principal tenses are followed by Principal, Historical by Historical. Thus:—
PRINCIPAL SEQUENCE,—
videō quid faciās, I see what you are doing.
vidēbō quid faciās, I shall see what you are doing.
vīderō quid faciās, I shall have seen what you are doing.
videō quid fēcerīs, I see what you have done.
vidēbō quid fēcerīs, I shall see what you have done.
vīderō quid fēcerīs, I shall have seen what you have done.
HISTORICAL SEQUENCE,—
vidēbam quid facerēs, I saw what you were doing.
vīdī quid facerēs, I saw what you were doing.
vīderam quid facerēs, I had seen what you were doing.
vidēbam quid fēcissēs, I saw what you had done.
vīdī quid fēcissēs, I saw what you had done.
vīderam quid fēcissēs, I had seen what you had done.
3. The Present and Imperfect Subjunctive denote incomplete action, the Perfect and Pluperfect completed action, exactly as in the Indicative.
Peculiarities of Sequence.
[268]. 1. The Perfect Indicative is usually an historical tense (even when translated in English as a Present Perfect), and so is followed by the Imperfect and Pluperfect Subjunctive; as,—
dēmōnstrāvī quārē ad causam accēderem, I have shown why I took the case (lit. I showed why, etc.).
2. A dependent Perfect Infinitive is treated as an historical tense wherever, if resolved into an equivalent Indicative, it would be historical; as,—