Tempora · Cōnsecūtiō Temporum

Latin distinguishes tense (when an action takes place: past / present / future) and aspect (whether the action is incomplete/in-progress vs. completed). These two dimensions crossbreed to produce the Latin six-tense system:

Incomplete aspect (present-system, formed from present stem):
• Present (amō): "I love / am loving" — action in progress now.
• Imperfect (amābam): "I was loving / used to love" — habitual or in-progress past.
• Future (amābō): "I shall love / will be loving" — incomplete future.

Completed aspect (perfect-system, formed from perfect stem):
• Perfect (amāvī): "I loved / have loved" — completed action, often viewed as result.
• Pluperfect (amāveram): "I had loved" — completed before some past reference point.
• Future-perfect (amāverō): "I shall have loved" — completed before some future reference point.

The Latin perfect is unique among Romance/Germanic equivalents in expressing both:

(a) "Aoristic" simple past: "I loved (once, then it ended)" — the Greek aorist sense, treating the action as a single completed event in the past.
(b) "Resultative" present-state: "I have loved (and the effect persists)" — the action is completed but its result is current.

Context decides which sense is operative. Caesar Galliam vīcit can mean "Caesar conquered Gaul" (event-based) or "Caesar has conquered Gaul" (state-based, with current consequence).

Historical present (praesēns historicum): Latin uses the present indicative for past narrative — vivid, dramatic effect. Caesar's celebrated vēnī, vīdī, vīcī uses perfects, but elsewhere Caesar (and Livy, Tacitus, Sallust) freely shifts to historical present in mid-narrative. Caesar venit, videt, vincit "Caesar comes, sees, conquers".

The historical present can blend with past narrative within a single passage; the choice often depends on which actions the writer wishes to highlight as immediate. The writer's perspective shifts in and out of the action.

Conative imperfect: the imperfect can express attempted but not necessarily successful action, or action with effort. persuādēbam "I was trying to persuade"; fugiēbat "he was trying to flee"; venīrent (subj.) in indir. discourse "they were trying to come".

Iterative imperfect: repeated or habitual action in past time. quotiēs venīret, mihi salūtem dīcēbat "whenever he came, he would greet me".

Inceptive imperfect: action just beginning. scrībēbam "I was (just starting to) write".

Epistolary tenses: in letters, the writer uses past tenses for actions present at the moment of writing, anticipating the reader's perspective at the moment of reading. haec scrībēbam "(I was writing this — when you read it)"; nihil habēbam quod scrīberem "I had nothing (= have nothing) to write".

Future-perfect: stronger temporal sequence than English. In subordinate clauses, future-perfect indicates an action completed before the future main clause. cum vēnerō, scrībam "when I (shall) have come, I will write" — fut.-perf. in subordinate where English uses simple present.

The Latin perfect tense (amāvī) is one form serving two functions:

(a) Aoristic perfect (also called perfectum historicum): treats the action as a single, completed event in the past. Translates English simple past: "I loved", "I saw", "he came". This is the perfect of narrative.

(b) Resultative perfect (also called perfectum logicum or praesēns perfectum): treats the action as completed and emphasizes its present result or consequence. Translates English present perfect: "I have loved", "he has come".

The choice between these affects the sequence of tenses (next section): an aoristic perfect counts as past (secondary sequence); a resultative perfect counts as present (primary sequence).

Caesar vēnit et omnēs vīcit = aoristic; secondary main verb in subordinate. Caesar Galliam vīcit; ergō rēx est = resultative; primary main verb.

This distinction does not exist morphologically — only the writer's intent (and your reading) determines which is meant. Latin offers no automatic way to disambiguate; English (with "did" vs "has done") and Korean (with 했다 vs 한 상태다) need to compute the sense from context.

The subjunctive has only four tenses (no future or future-perfect):

• Present (amem): incomplete present/future.
• Imperfect (amārem): incomplete past.
• Perfect (amāverim): completed action, present-relevant.
• Pluperfect (amāvissem): completed action, past-relevant.

The aspectual contrast persists: present and imperfect are incomplete; perfect and pluperfect are completed. The temporal contrast is preserved within each aspect.

Future time, when needed in subordinate subjunctive clauses (e.g., indirect questions, purpose clauses), is supplied by the periphrastic future active participle + present subjunctive of sum: amātūrus sim "I should be about to love" / "I will love (in subj. context)". This is essential for indirect questions about future actions: nesciō quid factūrus sit "I do not know what he is going to do".

The choice between present and imperfect (or between perfect and pluperfect) in dependent clauses is determined by the sequence of tenses rule, treated next.

The sequence of tenses (cōnsecūtiō temporum) is one of Latin's most rigorous grammatical rules. It governs which subjunctive tense is used in a subordinate clause, based on the tense of the main verb. The rule applies to subordinate clauses requiring the subjunctive: indirect questions, purpose clauses, result clauses, fearing clauses, indirect commands, characteristic relative clauses, anticipatory clauses, and the oblique subjunctive of indirect discourse.

Two tense-categories of main verbs:

(a) Primary: present indicative, future indicative, future-perfect indicative, true perfect (resultative). Time-frame: present or future.
(b) Secondary (Historical): imperfect indicative, perfect indicative (aoristic), pluperfect indicative. Time-frame: past.

Two relative-time choices in the subordinate clause:

• Action simultaneous with or subsequent to main verb.
• Action prior to main verb.

The rule:

Primary main verb →
• simultaneous/subsequent = present subjunctive
• prior = perfect subjunctive

Secondary main verb →
• simultaneous/subsequent = imperfect subjunctive
• prior = pluperfect subjunctive

This 2×2 = 4 combinations of mood-tense-relative-time covers most subordinate-clause subjunctive usage. Future relative time (when needed) uses the periphrastic -ūrus sim (primary) or -ūrus essem (secondary).