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,--

si hoc credis, erras, _if you believe this, you are mistaken_;

naturam si sequemur, numquam aberrabimus, _if we follow Nature, we
shall never go astray_;

si hoc dixisti, errasti, _if you said this, you were in error_.

2. Sometimes the Protasis takes the Indefinite Second Person Singular (Sec.
356, 3) of the Present or Perfect Subjunctive, with the force of the
Indicative; as,--

memoria minuitur, nisi eam exerceas, _memory is impaired unless you
exercise it_.

3. Here belong also those conditional sentences in which the Protasis
denotes a repeated action (compare Sec. 287, 2; 288, 3); as,--

si quis equitum deciderat, pedites circumsistebant, _if any one of the
horsemen fell, the foot-soldiers gathered about him_.

a. Instead of the Indicative, Livy and subsequent writers employ the
Subjunctive of the Historical tenses in the Protasis to denote repeated
action; as,--

si dicendo quis diem eximeret, _if (ever) anybody consumed a day in
pleading_; si quando adsideret, _if ever he sat by_.

4. Where the sense demands it, the Apodosis in conditional sentences of the
First Type may be an Imperative or one of the Independent Subjunctives
(Hortatory, Deliberative, etc.); as,--

si hoc creditis, tacete, _if you believe this, be silent_;

si hoc credimus, taceamus, _if we believe this, let us keep silent_.

Second Type.--'Should'-'Would' Conditions.

303. Here we regularly have the Subjunctive (of the Present or Perfect
tense) in both Protasis and Apodosis; as,--

si hoc dicas, erres, or si hoc dixeris, erraveris, _if you should say
this, you would be mistaken_;

si velim Hannibalis proelia omnia describere, dies me deficiat, _if I
should wish to describe all the battles of Hannibal, time would fail
me_;

mentiar, si negem, _I should lie, if I should deny it_;

haec si tecum patria loquatur, nonne impetrare debeat, _if your country
should plead thus with you, would she not deserve to obtain her
request?_

a. The Subjunctive in the Apodosis of conditional sentences of this type
is of the Potential variety.

b. Sometimes we find the Indicative in the Apodosis of sentences of the
Second Type, where the writer wishes t