§546. Cum Temporal

A temporal clause with cum and the Imperfect or Pluperfect Subjunctive describes the circumstances that accompanied or preceded the action of the main verb:—

• cum essem ōtiōsus in Tusculānō, accēpī tuās litterās (Fam. 9.18.1), when I was taking my ease in my house at Tusculum, I received your letter.
• cum servīlī bellō premerētur (Manil. 30), when she (Italy) was under the load of the Servile War.
• cum id nūntiātum esset, mātūrat (B. G. 1.7), when this had been reported, he made (makes) haste.
• cum ad Cybistra quīnque diēs essem morātus, rēgem Ariobarzānem īnsidiīs līberāvī; (Fam. 15.4.6), after remaining at Cybistra for five days, I freed King Ariobarzanes from plots.
• is cum ad mē Lāodicēam vēnisset mēcumque ego eum vellem, repente percussus est atrōcissimīs litterīs (id. 9.25.3), when he had come to me at Laodicea and I wished him to remain with me, he was suddenly, etc.

a. When the principal action is expressed in the form of a temporal clause with cum, and the definition of the time becomes the main clause, cum takes the Indicative.

Here the logical relations of the two clauses are inverted; hence cum is in this use called cum inversum:—

• diēs nōndum decem intercesserant, cum ille alter fīlius īnfāns necātur (Clu. 28), ten days had not yet passed, when the other infant son was killed. [Instead of when ten days had not yet passed, etc.]
• iamque lūx appārēbat cum prōcēdit ad mīlitēs (Q. C. 7.8.3), and day was already dawning when he appears before the soldiers.
• hōc facere noctū apparābant, cum mātrēs familiae repente in pūblicum prōcurrērunt (B. G. 7.26), they were preparing to do this by night, when the women suddenly ran out into the streets.