2069. The indicative in the protasis is occasionally replaced by the
subjunctive, as follows:
2070. (1.) The present or perfect subjunctive is sometimes used in
general present suppositions, regularly in the indefinite second person
singular, rarely with other persons (1730): as,
(_a._) #nam dolī nōn dolī sunt nisi astū colās, sed malum maxumum, sī id
palam prōvenit#, Pl. _Cap._ 221, _for tricks are never tricks, unless
you handle them with craft, but damage dire, in case the thing gets
out_; here the indicative #prōvenit# shows that #colās# is due to the
person. #nec calidae citius dēcēdunt corpore febrēs, textilibus sī in
pīctūrīs ostrōque rubentī iactēris, quam sī in plēbēiā veste cubandum
est#, Lucr. 2, 34, _nor sooner will hot fevers leave the limbs, if on
gay tapestries and blushing purple you should toss, than if perforce
your bed you make on pallet rude_. #quod est difficile, nisi speciem
prae tē bonī virī ferās#, _Off._ 2, 39, _and this is a hard thing,
unless you have the exterior of a good man_. #nec habēre virtūtem satis
est nisi ūtāre#, _RP._ 1, 2, _and to have virtue is not enough, unless
one use it_. #sīquoi mūtuom quid dederīs, fit prō propriō perditum#, Pl.
_Tri._ 1051, _if aught you’ve lent to anyone, ’tis not your own, but
lost_. #nam nūllae magis rēs duae plūs negōtī habent, sī occēperīs
exōrnāre#, Pl. _Poen._ 212, _for no two things give more trouble if you
once begin to fit them out_. #nūlla est excūsātiō peccātī, sī amīcī
causā peccāverīs#, _L._ 37, _it is no excuse for a sin if you have
sinned from friendship_.
(_b._) #suōs quisque opprimī nōn patitur, neque, aliter sī faciat, ūllam
inter suōs habet auctōritātem#, 6, 11, 4, _nobody suffers his vassals to
be put down, and if he ever act otherwise, he has no influence among his
people_. #laeduntur artēriae, sī ācrī clāmōre compleantur#, Cornif. 3,
21, _it always hurts the windpipe, if it be filled out with a sharp
scream_. #turpis excūsātiō est, sī quis contrā rem pūblicam sē amīcī
causā fēcisse fateātur#, _L._ 40, _it is always a discreditable apology,
if a man confess that he has been unpatriotic from motives of
friendship_. #Britannī iniūncta imperiī mūnera impigrē obeunt, sī
iniūriae absint#, Ta. _Agr._ 13, _the Britons are always perfectly ready
to perform the duties enjoined on them by the Roman government, if they
be not maltreated_.
2071. (2.) The imperfect or pluperfect subjunctive is sometimes used in
general past suppositions (1730).
This use begins with Catullus and Caesar, the indicative being the
regular classical construction (2044, 2050).
#chommoda dīcēbat, sī quandō commoda vellet dīcere Arrius#, Cat. 84, 1,
_hadvantages said Arrius, if advantages he ever meant to say_. #sī quis
prehenderētur, cōnsēnsū mīlitum ēripiēbātur#, Caes. _C._ 3, 110, 4,
_every time a man was taken up, he was rescued by the joint action of
the rank and file_. #sīn autem locum tenēre vellent, nec virtūtī locus
relinquēbātur, neque coniecta tēla vītāre poterant#, 5, 35, 4, _but if
on the other hand they undertook to hold their position, there was never
any opening for bravery, nor could they ever dodge the shower of
missiles_. #sīn Numidae propius accessissent, ibī̆ virtūtem ostendere#,
S. _I._ 58, 3, _they showed forth their valour every time the Numidians
drew near_ (1535).
(B.) SUBJUNCTIVE USE.
2072. The present or perfect subjunctive may be used in a conditional
protasis of future time.
2073. The apodosis is usually in the present subjunctive, less
frequently in the perfect subjunctive. The imperfect and pluperfect
subjunctive are rare (2089).
2074. The indicative is sometimes used in the apodosis, especially in
expressions of ability, duty, &c. (1495); #nōn possum# is regularly in
the indicative when the protasis is also negative. For the future
indicative the periphrastic form is sometimes used.
2075. In the early period, before the imperfect subjunctive had been
shifted to denote present time in conditional sentences (2091), the
present subjunctive was used to express action non-occurrent in present
time. Examples of this use are found in Plautus: as, #sī honestē cēnseam
tē facere posse, suādeam; vērum nōn potest; cave faxīs#, Pl. _MG._ 1371,
_if I thought that you could do the thing with credit to yourself,
I should advise you to; but ’tis impossible; so don’t you do it_. #vocem
tē ad cēnam, nisi egomet cēnem forīs#, Pl. _St._ 190, _I should ask you
home to dine, if I were not dining out myself_. Such sentences must not
be confused with those in which an action from the nature of things
impossible is represented as of possible occurrence.
(1.) PROTASIS IN THE PRESENT SUBJUNCTIVE.