How Prepositions Interact with Cases

Most Classical Latin prepositions govern either the accusative or the ablative. “Govern” means that the preposition requires its complement to appear in a particular case: ad urbem has accusative urbem, while ab urbe has ablative urbe. The case is part of the Latin construction, not a translation of the English preposition.

English “in,” “with,” and “from” each cover relations that Latin divides more finely. Conversely, Latin in can correspond to English “in,” “on,” “into,” “onto,” or “against,” depending on case and context. Learn a preposition together with its government and core spatial logic.

The two main groups

The following lists cover the most useful neutral Classical prose patterns.

The semantic descriptions explain tendencies, not a rule that generates every preposition. Apud “at, among, at the house of” takes the accusative even though it often describes a static location. Sine “without” takes the ablative because that is its inherited government. Some pairings must simply be learned.

The two location examples show why “static place = ablative” is not enough. The case is determined by the whole construction: apud governs an accusative, whereas sine and dē govern an ablative.

In and sub: goal versus location

With in and sub, case contributes a meaningful contrast. The accusative usually presents a destination or endpoint; the ablative presents a location in which something happens.

The presence of motion does not automatically trigger the accusative. Currunt in both sentences describes motion. What matters is whether the phrase locates the running inside the garden (in hortō) or makes entry into the garden its goal (in hortum).

The same location–goal contrast operates with sub. Context often makes the endpoint more idiomatic in English than a word-for-word “to under.” The page on accusative or ablative after in develops edge cases.

English equivalents do not choose the case

English “with” corresponds to at least two central Latin constructions:

The sister is a companion, so Latin uses cum plus ablative. The horse is the means of transport, so Latin uses a bare ablative. Adding cum would recast the horse as accompanying the traveler, not serving as the ordinary means.

English “from” also has several Latin analyses:

The common noun urbe follows ex. A town name in the standard place-from construction uses the bare ablative Rōmā. Latin omits prepositions with town names in certain place relations; this is a productive Classical pattern within a restricted noun class, not permission to omit them from common nouns.

Similarly, ad plus accusative is not a substitute for the dative recipient:

Ad Iūliam marks physical orientation or approach. Dative Iūliae marks the recipient of dat. English may use “to Julia” for both, but Latin keeps the relations distinct.

Pronouns with cum and phonological variants

With personal and reflexive pronouns, cum normally follows its complement: mēcum, tēcum, sēcum, nōbīscum, vōbīscum. With the relative or interrogative pronoun, both quōcum and cum quō occur. These are ordinary Classical forms, not a general rule that all prepositions may follow nouns.

The variants ā/ab and ē/ex are conditioned chiefly by sound. Ab and ex normally appear before vowels and can also appear before consonants; ā and ē appear before consonants. Fixed expressions and authorial rhythm create some variation, so learn to recognize both members of each pair.

Prepositions and larger functions

A prepositional phrase can modify a verb, noun, adjective, or an entire clause. Case government remains local even when the phrase's larger function changes.

Ā Mārcō marks a personal agent with a passive verb; per servum presents the slave as intermediary. Both can become English “by,” but their Latin analyses differ. A non-personal instrument normally uses the bare ablative: stilō scrībitur, “it is written with a stylus.”

This sentence contains three accusative-governing prepositions, but the phrases do different work: route (per silvam), goal (ad vīllam), and time before (ante noctem). Case alone does not supply the semantic subtype; the preposition does.

Register and historical boundaries

Neutral Classical prose normally places a preposition before its complement. (literary) Poetry may separate or postpone a preposition for meter and emphasis, and a few inherited words such as tenus behave as postpositions. (archaic) Early texts preserve constructions outside the later norm. In Late Latin, prepositional phrases expand as parts of the inherited case system weaken; those later developments should not be projected backward into Classical composition.

Some prepositions also develop abstract meanings: dē can mean “about,” prō “on behalf of” or “in place of,” and ob or propter “because of.” These are productive Classical extensions, but their case government remains unchanged.

Common Mistakes

1. Using the ablative after ad

2. Choosing accusative merely because there is motion

3. Using cum for an instrument

4. Using ad for a recipient

Key Takeaways

Most Latin prepositions lexically govern the accusative or ablative. With in and sub, accusative commonly marks a goal and ablative a location, but motion alone is not the test. English prepositions do not determine Latin case: learn the Latin construction, including its government, and then translate the relation naturally.