Ianitor dicit se portam urbis mox clausurum esse, quia nox obscura est.

It breaks into two main parts:

• Ianitor dicit se portam urbis mox clausurum esse = The gatekeeper says that he will soon close the city gate
• quia nox obscura est = because the night is dark

So the sentence consists of:

1. a main clause: Ianitor dicit
2. an indirect statement after dicit
3. a reason clause introduced by quia

Because Latin very often uses an accusative-and-infinitive construction after verbs of saying, thinking, knowing, hearing, and so on.

After dicit (says), Latin commonly does not say that he will close with a finite verb the way English does. Instead, it says:

• se = himself / he
• clausurum esse = to be about to close / to be going to close

So literally:

• Ianitor dicit se ... clausurum esse
  = The gatekeeper says himself ... to be going to close ...

More natural English:

• The gatekeeper says that he will soon close...

This construction is one of the most important features of Latin syntax.

Se is the reflexive pronoun in the accusative singular. In an indirect statement, the subject of the infinitive is put in the accusative case.

Here, se refers back to Ianitor. So:

• Ianitor dicit se... = The gatekeeper says that he...

Latin uses se rather than eum because the person doing the saying and the person who will do the action are the same person.

Compare:

• Ianitor dicit se portam clausurum esse = The gatekeeper says that he himself will close the gate
• Ianitor dicit eum portam clausurum esse = The gatekeeper says that he / that another man will close the gate

So se shows that the subject of the reported action is the same as the subject of dicit.

In Latin indirect statement, the subject of the infinitive goes into the accusative. This is the standard pattern:

• verb of saying/thinking/etc.
• accusative subject
• infinitive

So in this sentence:

• dicit = main verb
• se = subject of the infinitive, in accusative
• clausurum esse = infinitive phrase

Even though se is translated as he, grammatically it is accusative because Latin indirect statement requires that.

Clausurum esse is a future active infinitive.

It is made from:

• clausurum = future active participle of claudere (to close)
• esse = infinitive of to be

Together they mean:

• to be going to close
• to be about to close
• in smoother English here, will close

This form is how Latin expresses a future action inside an indirect statement.

Because clausurum agrees with se, which is accusative singular masculine.

The future participle changes form to agree with the subject of the infinitive:

• nominative masculine singular: clausurus
• accusative masculine singular: clausurum
• accusative feminine singular: clausuram

Since the implied person is the male gatekeeper, Latin uses clausurum.

If the subject were a woman, it would be:

• dicit se portam clausuram esse

Because the future active infinitive in Latin is normally formed with:

• future participle + esse

So:

• clausurum esse = to be going to close

Without esse, clausurum would just be a participle, not a complete infinitive phrase.

Because portam is the direct object of close.

The verb claudere takes a direct object in the accusative:

• portam claudit = he closes the gate

So in the indirect statement:

• se portam urbis mox clausurum esse
  = that he will soon close the city gate

Portam is accusative singular of porta.

Urbis is genitive singular of urbs, meaning city.

It depends on portam and means:

• the gate of the city
• more naturally, the city gate

So:

• porta urbis = the gate of the city

This is a very common Latin way to express possession or close association.

Yes, Latin could use either order.

Latin word order is more flexible than English because the endings show the grammatical relationships. So all of these would be understandable:

• portam urbis
• urbis portam

Similarly, mox could be placed in different positions.

That said, word order still affects emphasis and style. The given order is natural and straightforward.

Mox means soon.

It modifies clausurum esse, telling us when the closing will happen:

• se portam urbis mox clausurum esse = that he will soon close the city gate

Its position is fairly free. Latin often places adverbs near the word or phrase they modify, but not as rigidly as English.

You could also find:

• se mox portam urbis clausurum esse
• se portam urbis clausurum mox esse

though some positions sound more natural than others depending on style.

Because quia introduces a subordinate clause of reason: because...

So Latin uses a normal finite verb:

• quia nox obscura est = because the night is dark

This is different from the indirect statement after dicit. The infinitive construction is triggered by dicit; quia does not normally create that structure.

So the sentence has two different kinds of subordinate material:

• indirect statement after dicit
• causal clause after quia

Because the reason is presented as a present fact:

• the night is dark

Latin often keeps the tense that makes sense in the subordinate clause itself. The gatekeeper says he will close the gate soon because the night is dark now.

So:

• future action: clausurum esse
• present reason: nox obscura est

That combination is completely normal.

Because it agrees with nox, which is a feminine singular noun.

Latin adjectives agree with the nouns they describe in:

• gender
• number
• case

So:

• nox = feminine singular nominative
• obscura = feminine singular nominative

Together:

• nox obscura = dark night / the night is dark

Nox is nominative singular because it is the subject of est.

In the clause:

• nox obscura est

the structure is:

• nox = subject
• obscura = predicate adjective
• est = verb

So nox must be nominative.

Dicit means says. It is present tense because the sentence presents the speaking as happening now.

So the timeline is:

• now: the gatekeeper says
• soon afterward: he will close the gate

This is why the indirect statement needs a future idea inside it: the saying is present, but the closing is still in the future.

A good way is to identify each piece:

• Ianitor = the gatekeeper, subject of dicit
• dicit = says
• se = himself, subject of the infinitive
• portam = the gate, object of close
• urbis = of the city
• mox = soon
• clausurum esse = will close / to be going to close

So the gatekeeper is both:

1. the one who says
2. the one who will close the gate

That is exactly why se is reflexive.

It is literally a future infinitive, but in English it can be translated in several ways depending on context:

• will close
• is going to close
• is about to close

In this sentence, will soon close is probably the smoothest translation, especially because mox already expresses nearness in time.

Not in the same structure.

• clausurus est is a finite expression: he is about to close / he is going to close
• clausurum esse is the infinitive form needed inside indirect statement

So you could say directly:

• Ianitor portam urbis mox clausurus est
  = The gatekeeper is going to close the city gate soon

But after dicit, Latin normally changes to the indirect statement form:

• Ianitor dicit se portam urbis mox clausurum esse

Because Latin usually uses se when the subject of the indirect statement is the same as the subject of the main verb.

Repeating the noun would sound less natural in ordinary prose. The reflexive pronoun efficiently shows the connection:

• Ianitor dicit se... = The gatekeeper says that he...

This is one of the main jobs of se.

The key pattern is:

verb of saying + accusative subject + infinitive

Here:

• dicit = verb of saying
• se = accusative subject of the infinitive
• clausurum esse = infinitive expressing future action

So this sentence is an excellent example of Latin indirect statement, especially one that reports a future action. If you remember one model from it, remember:

• dicit se ... clausurum esse = he says that he will ...