Post iudicium fur in carcerem ducitur, sed soror eius extra carcerem flens manet.

Because post is a preposition that takes the accusative case when it means after.

So:

• post iudicium = after the trial/judgment

This is something you simply learn with the preposition:

• post
  • accusative = after

Here iudicium is the accusative singular form of iudicium, iudicii.

Both use the accusative, but for slightly different reasons.

• in carcerem = into the prison
• extra carcerem = outside the prison

With in, Latin often distinguishes:

• in
  • accusative = into / motion toward
• in
  • ablative = in / on / inside (location)

So fur in carcerem ducitur means the thief is being led into prison, not just in prison.

Meanwhile, extra is a preposition meaning outside and it normally takes the accusative:

• extra carcerem = outside the prison

Ducitur is the present passive of ducere (to lead).

• ducit = he/she leads
• ducitur = he/she is led

So:

• fur in carcerem ducitur = the thief is led into prison / the thief is being led into prison

Latin often uses the passive where English might also naturally use it, especially when the person doing the action is not mentioned.

You know because:

1. fur is in the nominative singular, the case normally used for the subject.
2. ducitur is third person singular, which matches fur.
3. The sentence structure supports it: the thief is led...

So:

• fur = subject
• ducitur = verb

Even though Latin word order is flexible, the case ending tells you the grammatical role.

Eius is the genitive singular form of the pronoun is, ea, id and means:

• of him
• of her
• of it

In context, soror eius means his sister.

Literally, it is closer to the sister of him, but natural English is his sister.

It modifies soror by showing possession.

A useful contrast:

• suus, sua, suum = his/her/its own (refers back to the subject of the clause)
• eius = his/her/its (someone else’s, not the subject of that clause)

Here the subject of the second clause is soror, so Latin does not use sua. The sister belongs to the thief, not to herself, so eius is correct.

Flens is the present participle of flere, meaning crying or weeping.

So:

• soror eius extra carcerem flens manet
  = his sister remains outside the prison, weeping

The participle adds an accompanying action or state:

• manet = remains / stays
• flens = crying

So she is staying there while crying.

Latin often uses participles this way more naturally than English does.

Flens is nominative singular feminine here, because it describes soror.

• soror = nominative singular feminine
• flens = nominative singular (same form for masculine/feminine in this participle)

It agrees with the noun it describes, just like an adjective does.

So flens means:

• weeping sister
• or more naturally in context, the sister, weeping, remains...

Manet is the present tense of manere, meaning remains or stays.

Latin often uses the present tense in straightforward narration, especially in simple teaching sentences. It can describe what is happening in the scene:

• ducitur = is led / is being led
• manet = remains / stays

This gives the sentence an immediate, vivid feel.

Classical Latin has no definite article (the) and no indefinite article (a/an).

So:

• fur can mean the thief or a thief
• carcerem can mean the prison or a prison
• soror can mean the sister or a sister

You decide from the context which English article is best. In this sentence, English naturally uses:

• the thief
• the prison
• his sister

Latin word order is much freer than English word order because Latin uses case endings to show grammatical roles.

English depends heavily on order:

• The thief leads the guard is different from The guard leads the thief

Latin can move words around more easily because endings show who is subject, object, and so on.

In this sentence:

• Post iudicium fur in carcerem ducitur, sed soror eius extra carcerem flens manet.

the order is perfectly normal Latin, but other arrangements could also be possible.

Word order in Latin often helps with:

• emphasis
• rhythm
• style

For example, flens placed near the end gives emotional emphasis to the sister’s state.

It can mean either, depending on context.

Iudicium has a range of meanings such as:

• judgment
• decision
• trial
• legal proceeding

In this sentence, because the thief is then led to prison, English learners will often understand post iudicium as after the trial. That is probably the most natural translation here.

But the broader idea is legal judgment or court proceedings.

Latin does not have to state who performs the action of a passive verb.

So:

• fur in carcerem ducitur = the thief is led into prison

The sentence does not say by whom. That is completely normal.

If Latin wanted to say by the guards, it could add an agent phrase, for example with ab + ablative.

But here the focus is on:

• the thief being taken away
• the sister remaining outside and weeping

So the doer of the action is left unstated.

It has two main clauses joined by sed (but).

1. Post iudicium fur in carcerem ducitur

   • Post iudicium = after the trial
   • fur = the thief
   • in carcerem = into prison
   • ducitur = is led

2. sed soror eius extra carcerem flens manet

   • sed = but
   • soror eius = his sister
   • extra carcerem = outside the prison
   • flens = weeping
   • manet = remains

So the sentence contrasts two things:

• the thief is taken away
• but his sister stays outside, crying

Yes. Depending on how natural you want the English to sound, you could translate flens as:

• weeping
• crying
• in tears
• while weeping
• as she weeps

Since it is a participle, English may render it in several ways. The important idea is that it describes the sister’s condition while she remains outside the prison.