Prepositions with accusative

Prepositions are the little words that show relationships - "into", "through", "toward". In Latin, every preposition demands that its noun stand in a particular case, and one large group requires the accusative. These prepositions typically involve motion toward or through something, so recognizing them tells you both the meaning and the ending to expect.

Preposition	Meaning	Example
ad	to, toward	ad villam - to the house
in (+ acc.)	into, onto	in silvam - into the forest
per	through	per viam - through the street
trans	across	trans flumen - across the river

Examples: Ad forum ambulamus. - We are walking to the forum. Puer in aquam currit. - The boy runs into the water.

For English speakers: in English the noun after a preposition never changes shape ("to the house", "the house is big"), so you have to remember that Latin re-shapes it: after these prepositions villa becomes villam. Pay special attention to in, which is a two-faced word - with the accusative it means motion "into" (in silvam, into the forest), but with the ablative it means rest "in" (in silva, in the forest). The ending on the noun is your clue to which meaning is intended.