a) The Future is supplied by the Present after principal tenses, by the Imperfect after historical tenses.
b) The Future Perfect is supplied by the Perfect after principal tenses, by the Pluperfect after historical tenses.
This is especially frequent when the context clearly shows, by the presence of a future tense in the main clause, that the reference is to future time. Thus:—
Gallī pollicentur sē factūrōs, quae Caesar imperet, the Gauls promise they will do what Caesar shall order;
Gallī pollicēbantur sē factūrōs, quae Caesar imperāret, the Gauls promised they would do what Caesar should order;
Gallī pollicentur sē factūrōs quae Caesar imperāverit, the Gauls promise they will do what Caesar shall have ordered;
Gallī pollicēbantur sē factūrōs quae Caesar imperāvisset, the Gauls promised they would do what Caesar should have ordered.
2. Even where the context does not contain a Future tense in the main clause, Future time is often expressed in the subordinate clauses by the Present and Imperfect Subjunctive. Thus:—
timeō nē veniat, I am afraid he will come;
Caesar exspectābat quid cōnsilī hostēs caperent, Caesar was waiting to see what plan the enemy would adopt.
3. Where greater definiteness is necessary, the periphrastic forms in -ūrus sim and -ūrus essem are employed, especially in clauses of Result, Indirect Questions, and after nōn dubitō quīn; as,—
nōn dubitō quīn pater ventūrus sit, I do not doubt that my father will come;
nōn dubitābam quīn pater ventūrus esset, I did not doubt that my father would come.
4. Where the verb has no Future Active Participle, or where it stands in the passive voice, its Future character may be indicated by the use of the particles mox, brevī, statim, etc., in connection with the Present and Imperfect Subjunctive; as,—
nōn dubitō quīn tē mox hūjus reī paeniteat, I do not doubt that you will soon repent of this thing;
nōn dubitābam quīn haec rēs brevī cōnficerētur, I did not doubt that this thing would soon be fnished.
TENSES OF THE INFINITIVE.
[270]. 1. The tenses of the Infinitive denote time not absolutely, but with reference to the verb on which they depend. Thus:—