In these clause types, English and Latin writers vary the indicative tenses, and there are numerous permutations. They may choose a specific tense since they have a particular idea in mind that they wish to convey, for example:
If you read that book, you will love it.
If you haven’t read that book, then I’m disappointed.
[i] There is often a parallel between the Latin verb usage and the English translations, for example:
Sī mē amās [present], ¦ cūrā [imperative], ut ... (Cicero)
- If you love me [present], ¦ [imperative] see to it that …
Tū sī litterās ad Sicyōniōs habēs [present], advolā [imperative] in Formiānum (Cicero)
- If you have [present], a letter to send to the Sicyonians, hasten [imperative] to Formiae.
Quid faciēmus [future], sī aliter nōn possumus [present]? (Cicero)
- What shall we do [future], if we cannot (do) otherwise [present]?
Sī fuit [perfect] invidiōsa senātūs potentia… quid iam cēnsēs [present] fore? (Cicero)
- If the power of the Senate was [simple past] unpopular … what do you think [present] it will be like now?
[ii] Where it differs most is when the conditional clause refers to the future. The distinction between the future and the future perfect in the conditional clause is whether the speaker is focussing on the action being carried out [future], or on the completion of the action [future perfect].
Mihi crēde, ¦ sī legēs [future] haec, ¦ dīcēs [future] mīrābilis vir est (Cicero)
- Trust me, if you read [present; La: will read] them, ¦ you will say “The man is a wonder.”
Latīnum sī perfēcerō [future perfect], ¦ ad tē mittam [future] (Cicero)
- [Latin (literally): If I shall have finished the Latin version, I shall send it to you.]
- If I finish [present] / If I have finished [present perfect] the Latin version, ¦ I shall send [future] it to you.
[iii] A subjunctive verb may be used in the apodosis:
Sī quid habēs certius, velim scīre (Cicero)
- If you have anything more certain, I would like to know.
The subjunctive in this context is not affecting the conditional clause but is simply being used independently to convey a polite request.
In this next example, a jussive subjunctive is used:
Quī hominēs quam prīmum, sī stāre nōn possunt, corruant (Cicero)
- If these men cannot stand, let them fall as soon as possible.
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Below are further examples; compare and contrast the verb usage.
Nunc, sī quid in eā epistulā, quam ante diem XVI Kal. Maiās dedistī, fuit historia dignum, scrībe quam prīmum (Cicero)
- So, if there was anything worth saying in the letter of the 16th of April, write at once.
Sī quī Graecī iam Rōmam ex Asiā … vēnērunt … (Cicero)
- If any Greeks have already come to Rome from Asia …
Quid iīs fīet, sī hūc Paulus vēnerit (Cicero)
- What will happen to them if Paulus comes [will have come] here?
Sī quid rēs feret, cōram inter nōs cōnferēmus (Cicero)
- If any point arises [will arise], we will discuss it together face-to-face.
Aliī sī scrīpserint, mittēmus ad tē (Cicero)
- If others (will) have written (about it), we shall send them to you.
Tū, sī tibi placuerit liber, cūrābis ut … (Cicero)
- If the book pleases [will have pleased] you, you will see to it that …
Eō sī ante eam diem nōn vēneris, Rōmae tē fortasse vidēbō (Cicero)
- If you do not get [will not have come] there before that date, perhaps I shall see you at Rome.
Sī dīxerō mendācium, solēns meō mōre fēcerō (Plautus)
- If I tell [shall have told] a lie, I shall have done so as I usually do according to my custom.
Tū, sī ūnō in locō es futūrus, crēbrās ā nōbīs litterās exspectā (Cicero)
- If you are going to be in one place, expect many letters from us.
Intereā scrībās [subjunctive], sī quid intellegēs (Cicero)
- Meanwhile, if you learn anything, you should write to me
Sī iam es Rōmae … velim [subjunctive] mittās … (Cicero)
- If you are already in Rome, I would like you to send …
An overdose of conditional clauses:
Quam ob rem, sī mē amās tantum, quantum profectō amās, sī dormīs, expergīscere, sī stās, ingredere, sī ingrederis, curre, sī curris, advolā. (Cicero)
Quam ob rem, sī mē amās tantum, quantum profectō amās, … │ Therefore, if you love me as much as you really love me …
sī dormīs, expergīscere │ if you are sleeping, wake up
sī stās, ingredere │ if you are standing, get moving
sī ingrederis, curre │ if you are moving, run
sī curris, advolā │ if you are running, fly
