Infra pontem rivus celeriter currit, et septem anates contra aquam natant.

Because infra is a preposition that normally takes the accusative. So infra pontem means below the bridge or under the bridge.

This can feel strange to an English speaker, because English does not show this kind of case change. In Latin, the preposition often determines the case of the noun that follows it. Here:

• infra = below, beneath
• pontem = bridge in the accusative singular

So the accusative here is not showing a direct object; it is there because infra requires it.

For the same general reason: contra is another preposition that takes the accusative.

So:

• contra = against
• aquam = water, in the accusative singular

Together, contra aquam means against the water. In natural English, this often means against the current or upstream.

Rivus is in the nominative singular, which is the case normally used for the subject. Also, the verb currit is third person singular, so it matches a singular subject.

So:

• rivus = stream, brook, nominative singular
• currit = he/she/it runs, is running

That tells you the stream is the thing doing the action.

The verb natant is third person plural, so it needs a plural subject. Anates is the plural form of anas, meaning ducks.

So:

• anates = ducks
• natant = they swim, are swimming

A beginner may notice that anates could look like an object form too, and that is true in form: for this noun, nominative plural and accusative plural are the same. But here natant is an intransitive verb, so anates must be the subject.

Latin word order is much more flexible than English word order because Latin uses case endings to show how words function in the sentence.

English depends heavily on position:

• The stream runs under the bridge

Latin can move parts around more freely:

• Infra pontem rivus celeriter currit

Even with this different order, the endings tell you what each word is doing. The sentence begins with infra pontem to set the scene first: under the bridge.

Celeriter is an adverb, and it modifies currit. It means quickly.

So:

• rivus currit = the stream runs / flows
• rivus celeriter currit = the stream runs / flows quickly

A common pattern in Latin is that many adverbs are formed from adjectives. Here celeriter is related to celer, meaning quick.

Latin often uses currere not only for literal running, but also for things like flowing. So a stream can run, just as English also says the river runs through the valley.

In this sentence:

• rivus currit literally = the stream runs
• natural English meaning = the stream flows

So this is a normal and idiomatic use of currere.

Yes. Both are present active indicative forms.

• currit = it runs / it is running
• natant = they swim / they are swimming

Latin present tense can often be translated in more than one way in English, depending on context:

• simple present: runs, swim
• progressive present: is running, are swimming

Classical Latin has no articles. That means it does not have separate words for the, a, or an.

So:

• rivus can mean a stream or the stream
• pontem can mean a bridge or the bridge
• anates can mean ducks or the ducks

You decide which English article fits best from the context.

Septem is an indeclinable numeral, meaning its form does not change for case, gender, or number.

So:

• septem anates = seven ducks

Unlike adjectives such as bonus, bona, bonum, septem stays septem no matter what noun it goes with. The noun itself still appears in the form the sentence requires.

No. Aquam is not the direct object of the verb. It is the object of the preposition contra.

So the structure is:

• natant = they swim
• contra aquam = against the water

Together: they swim against the water.

This is important because English speakers often look for a direct object after the verb, but here the accusative is caused by the preposition, not by the verb.

Yes, Latin could often express a similar idea with sub. But there is a small grammatical difference in how these prepositions behave.

• sub with the ablative often means position: under
• sub with the accusative often suggests motion toward a position under something
• infra commonly takes the accusative

So:

• sub ponte = under the bridge
• infra pontem = below the bridge / under the bridge

In this sentence, infra pontem is perfectly good Latin and simply gives the location of the stream.

It is made of two main clauses joined by et.

First clause:

• Infra pontem rivus celeriter currit
• Under the bridge, the stream flows quickly

Second clause:

• et septem anates contra aquam natant
• and seven ducks swim against the water

So et simply connects two complete statements:

• the stream flows quickly
• seven ducks swim against the water