Indicative or Subjunctive after Cum?

The conjunction cum can introduce a fact that merely locates another event in time, or it can frame that event as part of its circumstances, cause, or concession. Latin normally uses the indicative for plain temporal facts and regular recurrence, but the subjunctive for circumstantial narrative, causal cum (“since”), and concessive cum (“although”). English “when” can represent all of these relations, so translating the conjunction first is a poor diagnostic.

First make sure the word is a conjunction. Prepositional cum takes an ablative—cum amīcō, “with a friend”—and has no following finite verb whose mood must be chosen. This page concerns conjunction cum followed by a clause.

The decision in one table

Indicative: time stated as fact

Use the indicative when cum marks an actual time relation without presenting the subordinate event as cause, concession, or narrative background. This includes repeated situations and many present or future relations.

The first uses presents for a recurring fact. The second uses future perfect advēnerō because arrival will be complete before vocābō. English normally says “when I arrive,” but Latin explicitly marks future anteriority.

A particular past event can also take the indicative when the author treats the clause as a straightforward date or coincidence rather than as the setting of historical narrative.

That sentence reports two facts. A writer may instead choose a subjunctive to make the first event attendant circumstance; the difference is viewpoint, not truth versus unreality.

Historical cum: circumstance in past narrative

In Classical narrative, cum commonly takes the imperfect or pluperfect subjunctive. The imperfect presents a simultaneous or ongoing circumstance; the pluperfect presents a circumstance completed before the main event.

The mood signals subordination into the narrative frame. Tense then locates the subordinate situation relative to the main past event: dormīrent is simultaneous; discessissent is anterior. This follows the Sequence of Tenses, not an English rule that subjunctive means “might” or “would.”

Causal cum: “since” or “because”

When the cum-clause supplies the speaker’s reason for the main clause, use the subjunctive. The cause can be present, prior, or past; normal sequence of tenses supplies the form.

Do not infer cause merely because one event precedes another. In cum haec audīvit, rīsit, hearing dates the laughter. In cum haec audīvisset, sententiam mūtāvit, context may invite “since he had heard this”: the hearing is presented as explanatory circumstance.

Concessive cum: “although”

Concessive cum also takes the subjunctive and is commonly answered by tamen “nevertheless” in the main clause. Tamen is a valuable production and parsing signal, though Latin can omit it when the contrast is obvious.

The subjunctive does not make tiredness or opposition doubtful. It marks the logical relation: the circumstance might have been expected to prevent the main event, yet did not.

Six contrasts: same conjunction, different relation

1. Cum Lūcius venit, iānuam aperimus.

   Whenever Lucius comes, we open the door. (recurring temporal fact)

   Cum Lūcius venīret, iānuam aperuimus.

   As Lucius was coming, we opened the door. (past circumstance)

2. Cum hostēs appropinquābant, cōnsul Rōmae erat.

   When the enemy were approaching, the consul was at Rome. (plain dating)

   Cum hostēs appropinquārent, cōnsul portās clausit.

   As the enemy were approaching, the consul closed the gates. (narrative frame)

3. Cum hoc audīvit, discessit.

   When he heard this, he left. (temporal event)

   Cum hoc audīvisset, discessit.

   Since/after he had heard this, he left. (anterior circumstance; context decides causal shading)

4. Cum pecūniam habet, librōs emit.

   Whenever he has money, he buys books.

   Cum pecūniam habeat, tamen librōs nōn emit.

   Although he has money, he does not buy books.

5. Cum magister intrāvit, discipulī cōnsurrēxērunt.

   When the teacher entered, the students stood up. (two dated facts)

   Cum magister intrāret, discipulī inter sē loquēbantur.

   As the teacher was entering, the students were talking among themselves. (scene-setting)

6. Vix cōnsēderāmus, cum nūntius vēnit.

   We had scarcely sat down when a messenger arrived. (inverted cum with indicative)

   Cum nūntius vēnisset, cōnsilium cēpimus.

   After the messenger had arrived, we formed a plan. (historical circumstance)

The sixth contrast shows cum inversum. After vix, vixdum, or a similar expression, the main clause describes the state just reached and the cum-clause introduces the interrupting event. Because that event is foregrounded as a fact, the indicative is normal. This pattern is especially characteristic of narrative prose (formal/literary).

Fixed and marked patterns

Cum prīmum “as soon as” normally stresses temporal sequence and favors the indicative. Correlative cum … tum can mean “both … and especially”; its logic is not the historical-circumstantial construction. Early Latin often retains the indicative even with causal or concessive quom (archaic); that older distribution is not the productive Classical prose rule. Poets may also extend or compress prose patterns for meter and style (literary). These facts should be recognized, not used to erase the productive Classical opposition.

Short decision drill

1. “Whenever the dog sees me, it barks.” → indicative: Cum canis mē videt, lātrat. This is recurring fact.
2. “When the dog was barking, the child woke.” → imperfect subjunctive: Cum canis lātrāret, īnfāns experrēctus est. The barking frames a past event.
3. “Since you have understood the danger, leave.” → perfect subjunctive: Cum perīculum intellēxerīs, discēde. The clause gives the reason; intellēxerīs marks prior completion in primary sequence.
4. “Although the road was long, we continued.” → imperfect subjunctive plus tamen: Cum via longa esset, tamen perrēximus. The relation is concessive.
5. “I had barely finished the letter when someone opened the door.” → indicative in inverted cum: Vix epistulam perfēceram, cum aliquis iānuam aperuit. The opening is the foregrounded interruption.

Common Mistakes

1. Using the indicative after every English “when”

2. Treating every past cum as historical cum

3. Using the indicative because the cause is certain

4. Forgetting tamen in an otherwise unclear concession

Choose the relation first, the mood second, and the tense third. That order prevents English “when” from concealing the Latin structure.

Key Takeaways

• Plain temporal fact favors the indicative; historical circumstance, cause, and concession favor the subjunctive.
• With historical cum, imperfect subjunctive marks simultaneous background and pluperfect subjunctive prior background.
• Inverted cum foregrounds the interrupting event and normally takes the indicative.