B. Tenses of the Subjunctive.

[318]. These follow the regular principle for the Sequence of Tenses, being Principal if the verb of saying is Principal; Historical if it is Historical. Yet for the sake of vividness, we often find the Present Subjunctive used after an historical tense (Repraesentātiō); as,—

Caesar respondit, sī obsidēs dentur, sēsē pācem esse factūrum, Caesar replied that, if hostages be given, he would make peace.

a. For the sequence after the Perfect Infinitive, see [§ 268], 2.

CONDITIONAL SENTENCES IN INDIRECT DISCOURSE.

Conditional Sentences of the First Type.

[319]. A. THE APODOSIS. Any tense of the Indicative is changed to the corresponding tense of the Infinitive ([§§ 270]; [ 317], a).

B. THE PROTASIS. The protasis takes those tenses of the Subjunctive which are required by the Sequence of Tenses.

Examples:—

DIRECT. INDIRECT.
sī hōc crēdis, errās, dīcō, sī hōc crēdās, tē errāre;
dīxī, sī hōc crēderēs, tē errāre.
sī hōc crēdēs, errābis, dīcō, sī hōc crēdās, tē errātūrum esse;
dīxī, sī hōc crēderēs, tē errātūrum esse.
sī hōc crēdideris, errābis, dīcō, sī hōc crēderīs, tē errātūrum esse;
dīxī, sī hōc crēdidissēs, tē errātūrum esse.
sī hōc crēdēbās, errāvistī, dīcō, sī hōc crēderēs, tē errāvisse;
dīxī, sī hōc crēderēs, tē errāvisse.