Maneant pueri sub porticu, donec faber opus in tecto finiat.

Maneant is the present subjunctive, not the indicative. Here it is a jussive subjunctive, which Latin often uses to give a command about a third person:

• manent = they remain / are remaining
• maneant = let them remain

So the sentence is not simply describing what the boys do; it is telling what they are to do.

Because manete would mean stay! said directly to you all. That is a second-person plural command.

But pueri means the boys, which is third person. Latin commonly uses the jussive subjunctive for third-person commands:

• manete = you all stay
• maneant pueri = let the boys stay

English does something similar with let ....

Here pueri is nominative plural, the subject of maneant.

You can tell because:

• maneant is third-person plural
• the subject must therefore also be plural
• pueri fits as the boys

A learner may notice that pueri can also be genitive singular in other contexts, but here the verb makes it clear that it must be nominative plural.

Because sub changes case depending on the idea:

• sub + ablative = under in the sense of location
• sub + accusative = to under / underneath in the sense of motion toward

Here the boys are already staying there, not moving there, so Latin uses the ablative:

• sub porticu = under the portico
• sub porticum would suggest movement toward a position under it

Porticu is the ablative singular of porticus, -ūs, a fourth-declension noun.

That is why the ending is -u instead of the more familiar -o or -a. A native English speaker learning Latin often expects every noun to behave like first- or second-declension nouns, but porticus belongs to a different pattern.

Because the sentence is looking ahead to an action that has not yet happened: the boys are to remain there until the builder finishes.

With donec (until), Latin can use either the indicative or the subjunctive, depending on nuance. Here the subjunctive presents the finishing as something anticipated or pending, not yet an accomplished fact from the speaker’s point of view.

So donec ... finiat is basically until ... finishes / should finish.

Finiat is the present active subjunctive, third-person singular, of finio, finire.

It agrees with faber:

• faber finiat = the builder/craftsman may finish or, in this sentence, until the builder finishes

Even though English may think of this as future in sense, Latin often uses the present subjunctive in a subordinate clause like this.

Opus is the direct object of finiat: it is the thing the builder finishes.

Grammatically, it is accusative singular neuter.

A useful point: with many neuter nouns, the nominative and accusative singular look the same. So opus can be either nominative or accusative depending on context. Here it must be accusative because it is the object of finiat.

For the same reason as sub porticu:

• in + ablative = location
• in + accusative = motion into/onto

Here the work is located there, so Latin uses the ablative:

• in tecto = in/on the roof or on the house, depending on context

Latin in with the ablative does not always match English in exactly; depending on the noun, it may be best translated as in, on, or at.

Because Latin has no definite or indefinite article. It does not have separate words for the, a, or an.

So:

• pueri can mean boys or the boys
• faber can mean a builder or the builder
• opus can mean work, the work, or a piece of work

The context tells you which English article is natural.

It may feel unusual to an English speaker, but it is normal Latin. Latin word order is much more flexible because the endings show the grammatical roles.

A very literal layout is:

• Maneant — let remain
• pueri — the boys
• sub porticu — under the portico
• donec — until
• faber — the builder
• opus — the work
• in tecto — on the roof
• finiat — finishes

Latin often places the verb late, especially in subordinate clauses, so the final finiat is very natural Latin style.

It has two parts:

1. Main clause: Maneant pueri sub porticu

   • a jussive subjunctive
   • Let the boys remain under the portico

2. Subordinate clause: donec faber opus in tecto finiat

   • a donec clause showing the time limit
   • until the builder finishes the work on the roof

So the whole sentence means: the boys are to stay where they are, and the donec clause tells you how long.