6. In early Latin and in poetry the Indicative is sometimes used in indirect Questions.
CONDITIONAL SENTENCES.
[301]. Conditional Sentences are compound sentences ([§ 164]) consisting of two parts, the Protasis (or condition), usually introduced by sī, nisi, or sīn, and the Apodosis (or conclusion). There are the following types of Conditional Sentences:—
First Type.—Nothing Implied as to the Reality of the Supposed Case.
[302]. 1. Here we regularly have the Indicative in both Protasis and Apodosis. Any tense may be used; as,—
sī hōc crēdis, errās, if you believe this, you are mistaken;
nātūram sī sequēmur, numquam aberrābimus, if we follow Nature, we shall never go astray;
sī hōc dīxistī, errāstī, if you said this, you were in error.
2. Sometimes the Protasis takes the Indefinite Second Person Singular ([§ 356], 3) of the Present or Perfect Subjunctive, with the force of the Indicative; as,—
memoria minuitur, nisi eam exerceās, memory is impaired unless you exercise it.
3. Here belong also those conditional sentences in which the Protasis denotes a repeated action (compare [§§ 287], 2; [ 288], 3); as,—
sī quis equitum dēciderat, peditēs circumsistēbant, if any one of the horsemen fell, the foot-soldiers gathered about him.