Latin Reference — Vol. I: The Case System

The six working cases

Pithy anchors: genitive = of/'s · dative = to/for · ablative = by/with/from/in. Lock those in and half the battle is won.

Working cases because there is a seventh, the locative, surviving only in scraps — names of towns and small islands, plus a few fossils (Rōmae, domī at home, rūrī in the country). It does one job, on a closed list of words, and everything else that might have used it went to the ablative long before the Latin you'll be reading. Meet it when you meet it; don't drill it.

Prepositions and the cases they trigger

Latin prepositions are locked to specific cases — spotting the preposition tells you the case of the next noun.

Accusative triggers (often motion toward, through or against — but the case is a property of each preposition, and several common ones are purely positional)

Note the positional exceptions: inter, circum, ante, post and prope all take the accusative while describing where something simply is. Ōstia est prope Rōmam — Ostia isn't going anywhere. The motion gloss explains the pattern's origin, not every member of it: learn the list, and let the in/sub rule below carry the logic.

Ablative triggers (broadly: source, separation, accompaniment)

The in/sub rule: in and sub take accusative for motion (in urbem — into the city) and ablative for location (in urbe — in the city). It looks irregular but is the most logical thing in the language: accusative marks goals; ablative marks where you already are.

Why ad (acc) but ab (abl) when both involve motion? Accusative marks goals and targets; ablative marks sources and separation. Ablative itself derives from ab + lātum, "carried away from".

Aside — near and far. Textbooks pair prope Rōmam with procul ab Rōmā — near Rome, far from Rome — and the pair is worth holding onto, because the case difference isn't about distance at all. Procul is an adverb; the case-work in that phrase is done by ab, a separation word, hence ablative. Nearness takes the accusative because prope says so. Its relatives propior (nearer) and proximus (nearest) reach English as approach, proximity and propinquity — and approach is the one place the accusative's target sense still shows through.

Declension endings

First declension (f.) — puella

Second declension (m.) — amīcus

Second declension (n.) — templum

Neuter rule: nominative and accusative are always identical, and the plural of both is always -a.

Third declension (m./f.) — mīles, mīlitis

Third declension nominatives are irregular; the genitive singular reveals the stem (mīles → mīlit-). Dictionaries list both for this reason.

One noun, all cases — puella

This is the table to drill: reading one noun shift through seven contexts is what makes the pattern click — and the last two rows are the point of this volume in miniature, the same ending doing motion and position depending only on which preposition is standing in front of it.