Accusative Subject of the Infinitive

An infinitive can head a clause of its own in Latin. When that clause has an expressed subject, the subject normally appears in the accusative, not the nominative: Mārcum venīre means “that Marcus is coming” or, in another environment, “Marcus to come.” This is a syntactic use of the accusative. Marcus is not receiving the action of “come,” and no fixed English preposition explains his case.

The basic structure

Compare an independent statement with the same proposition embedded after a verb of knowing:

In the first sentence, finite venit has the nominative subject Mārcus. In the second, venīre is infinitive and its subject is accusative Mārcum. English usually turns the whole infinitival clause into a finite that-clause, so English “Marcus” does not reveal the Latin case.

The construction is traditionally called accusative and infinitive (accūsātīvus cum īnfīnītīvō, often “AcI”). Its shape is:

What governs the construction

The pattern is productive in ordinary Classical prose after predicates of saying, thinking, knowing, learning, perceiving, and reporting. The governing word can be a verb or an impersonal expression.

In portās clausās esse, portās is the subject of the perfect passive infinitive. Clausās is also accusative because the participle is predicated of and agrees with that subject. This agreement is an excellent diagnostic: the accusative phrase belongs inside the infinitival clause.

Impersonal predicates can take the entire infinitival clause as their grammatical subject:

Here Caesarem is not an object of cōnstat. The proposition Caesarem vēnisse is what “is established,” and Caesarem is the subject within that proposition. English “it” is only a dummy subject used to package the translation.

Verbs of ordering, permitting, and preventing create a neighboring pattern:

The soldiers are both the people ordered by iubet and the understood agents of reficere. Grammarians therefore describe mīlitēs either as the object of the governing verb controlling the infinitive or, from the embedded clause’s perspective, as the infinitive’s subject. The overlap is real; it is not resolved by word order. See the dedicated page on iubeō, vetō, and sinō for their passive behavior.

Relative time inside indirect statement

The infinitive has no person ending, but its tense locates its event relative to the governing verb. With an accusative subject, the central three-way contrast is:

The future participle ventūrum is masculine singular accusative because it agrees with Mārcum. English changes “will” to “would” after a past reporting verb; Latin instead preserves the relative future relation with ventūrum esse. Full tense selection belongs to tense relations in infinitives.

Pronouns and coreference

Unlike an ordinary finite Latin verb, an infinitive does not mark person. Its subject therefore normally remains explicit when the proposition is reported, even when it refers to the speaker or to the subject of the governing verb.

First-person mē refers to the speaker. Third-person reflexive sē in indirect statement normally refers back to the subject whose thought or speech is being reported. The adjective follows the accusative: a female speaker says mē parātam esse. Non-reflexive eum or eam points to someone else in the context.

Classical authors can nevertheless omit an accusative subject when context makes it unmistakable. That is contextual ellipsis, not evidence that indirect statement and the complementary infinitive have become the same construction. For clear neutral prose, especially where two possible referents are present, explicit mē, sē, eum, or eam prevents ambiguity.

A reliable parsing test

When an accusative stands near an infinitive, use this sequence:

1. Identify the governing word and ask whether it can introduce reported content, perception, evaluation, or a command.
2. Bracket the likely infinitival clause.
3. Ask who performs or undergoes the infinitive. Do not ask which noun comes first.
4. Look for an accusative predicate adjective, noun, or participle agreeing with that participant.
5. Only then translate the whole clause as English that + finite verb or object + to-infinitive.

Both eum and bonum medicum are accusative, but they are not two direct objects. Eum is the embedded subject; bonum medicum is its predicate complement. English word order happens to put “him” after “believe,” which tempts an object analysis, but esse and the agreement expose the clause.

The AcI is unmarked in Classical prose. Long stretches of indirect discourse are especially common in (formal) historiography and forensic prose. (literary) poetry may omit easily recoverable forms of esse or arrange the accusative and infinitive far apart. Later Latin increasingly admits finite clauses with quod or quia where Classical prose prefers an AcI; that later development should not be projected back as the default Classical pattern.

Two marked constructions explain why the rule says “normally.” The historical infinitive replaces a finite narrative verb and takes a nominative subject. A reporting verb used in the personal passive construction likewise has a nominative subject: Mārcus venīre dīcitur means “Marcus is said to be coming.” Neither pattern is the ordinary active AcI illustrated above.

Common Mistakes

1. Leaving the embedded subject nominative

2. Treating the accusative as the infinitive’s object

3. Using a non-reflexive pronoun for the speaker of the indirect statement

4. Choosing the case from English for

Key Takeaways

An expressed subject of a Latin infinitive is normally accusative. Diagnose it from its role inside the infinitival clause, from agreement, and from the governing predicate—not from English order or an English preposition. Keep true indirect statement distinct from a complementary infinitive and recognize that verbs such as iubeō produce a genuine overlap between matrix object and infinitival subject.