Relative Clauses of Purpose

A relative clause of purpose uses a relative word and a subjunctive to say what someone or something is selected, sent, provided, or otherwise involved to do: mīlitēs mīsit quī pontem custōdīrent, “he sent soldiers to guard the bridge.” The antecedent mīlitēs is not merely being described. Their intended function is to guard.

English commonly replaces the whole clause with an infinitive, so “soldiers who would guard” can sound unnatural. Latin preserves the relative relationship: quī agrees with mīlitēs in gender and number, takes its case from its role inside the purpose clause, and introduces a subjunctive governed by sequence of tenses.

The core construction

The present vocat takes primary sequence curet; historic mīsit takes imperfect custōdīrent. The relative pronoun is nominative in both because it is the subject of its clause. The subjunctive marks purposeful framing, not uncertainty about whether the doctor or soldiers exist.

A reliable parsing procedure

First identify the relative word and its antecedent. Then assign the relative word a case from its job inside its own clause. Next identify the subjunctive and apply sequence of tenses. Finally ask whether the main clause presents the antecedent as a person, object, place, or means suited to an intended task.

Quem is masculine singular because its antecedent is servum, but accusative because it is the object of mittāmus. English-speaking learners often make it nominative by mechanically matching the antecedent’s apparent role. Agreement determines gender and number; clause-internal syntax determines case.

Here quibus is ablative plural, agreeing in gender and number with tabellās and expressing the surface or means on which the children write. The subject of scrīberent is understood from puerīs, not from quibus.

Sequence and time relationship

Relative purpose follows the ordinary purpose-clause sequence: a primary main verb normally takes present subjunctive, while a historic main verb normally takes imperfect subjunctive. The purposeful act is ordinarily simultaneous with or later than the provision described by the main clause.

English “can/could” is natural here, but it is not a literal tense-by-tense decoding. Legam and legeret are active subjunctives whose clause describes the intended use of the place. See Sequence of Tenses for exceptional contextual sequences.

Latin has no simple future subjunctive, so a future main verb still normally takes present subjunctive:

The ablative quā expresses means or conveyance and agrees with feminine singular nāvem. Present vehāmur is passive in form and supplies the primary-sequence purpose; it is not a future subjunctive.

Relative purpose versus an ordinary relative fact

An indicative relative clause asserts a fact about its antecedent. A purpose relative frames the clause as the intended role for which the antecedent enters the situation.

In the first, the men were already identifiable as bridge guards; the relative clause describes them. In the second, guarding is the mission associated with sending them. The imperfect subjunctive does not mean “perhaps guarded” or automatically “would guard.” It shows that the relative clause is subordinate purposeful framing in historic sequence.

A relative clause of characteristic can also use the subjunctive: nēmō est quī hoc faciat, “there is no one who would do this.” That construction characterizes a class or type rather than assigning an antecedent a task. The difference comes from the main clause and discourse meaning, not from the relative form alone.

Relation to an ut purpose clause

A relative purpose construction highlights an antecedent that fills a grammatical role inside the dependent clause. An ut clause states the goal without building that relative link.

Both are correct and close in meaning. The relative version integrates legātōs as the antecedent and subject of quī; the ut version leaves the subject to be recovered from context. This alternation is productive in ordinary Classical prose, especially after verbs of sending, choosing, giving, seeking, and having.

Negation

To negate the verb inside a relative purpose clause, nōn is the straightforward negator: quī nōn cēderet, “who was not to yield.” If the central meaning is active prevention—“so that X would not happen”—Classical Latin normally prefers a separate nē purpose clause rather than forcing every negative goal into relative form.

The first assigns a negative duty to the guard; the second presents the prevention of entry as the goal of posting him. This distinction is semantic, not a ban on negative relative clauses. For productive negative prevention, see Negative Purpose Clauses with Nē.

Relative adverbs of purpose

Purpose need not be introduced by a form of quī. Relative adverbs can connect an intended place, source, or direction to an antecedent: ubi “where,” unde “from where,” and quō “to where.” Such prose is neutral or (formal) according to the surrounding style, not inherently poetic.

The antecedent portum provides the destination; quō restates that directional role inside the clause. Do not confuse adverbial quō “to which place” with ablative singular quō “by which.”

An authentic prose example

Caesar’s envoys commonly appear in this construction. In the following excerpt, spelling is reproduced without pedagogical macrons:

Quī dīcerent is historic-sequence relative purpose after the historical present mittunt. The imperfect reflects the narrative’s historic temporal frame even though the main verb is morphologically present—an important feature of the (literary/formal) historical present.

Common Mistakes

Using an indicative for an intended assignment

Copying the antecedent’s case onto the relative pronoun

Choosing the subjunctive merely because English says “would”

Ignoring historic sequence

Key Takeaways

Find the antecedent, determine the relative word’s gender and number from that antecedent, assign its case inside the dependent clause, and then apply purpose-clause sequence. The subjunctive marks an intended function; it does not inherently mean “would.” An indicative relative asserts a description, while a purpose relative assigns the antecedent a role in someone’s plan.