Una tegula de tecto cecidit, sed faber dicit trabem et fornices firmos manere.

Because tegula is a feminine noun, and una has to agree with it in gender, number, and case.

• tegula = feminine singular nominative
• una = feminine singular nominative

So una tegula means one tile or a single tile.

Latin adjectives and adjective-like words such as unus, una, unum must match the noun they describe.

Strictly speaking, una means one. So the phrase most literally means one tile or a single tile.

This matters because Latin has no definite or indefinite article:

• no word for the
• no word for a/an

So:

• tegula could mean a tile or the tile, depending on context
• una tegula adds the idea of one single tile

In this sentence, una may simply highlight that only one tile fell, not the whole roof.

Tegula is nominative singular. It is the subject of cecidit.

You can tell because:

• tegula is the thing doing the action of falling
• the basic dictionary form of the noun is tegula
• in a simple sentence, the subject is usually in the nominative

So in Una tegula de tecto cecidit, the subject is una tegula.

Tecto is ablative singular, because the preposition de takes the ablative.

• de = from, down from, about, concerning
• tectum = roof
• de tecto = from the roof / down from the roof

Here de is especially natural because the tile falls down from the roof. Latin often uses de when something comes off the top of something.

Because de often suggests movement down from a surface or higher place.

Compare the general ideas:

• de = down from, off
• ex / e = out of, out from inside
• ab / a = away from, from the vicinity of

A tile does not come out of the roof as if it were inside it; it falls off or down from it. So de tecto is the most natural choice.

Cecidit is perfect tense of cadere.

• cadit = falls / is falling
• cecidit = fell or has fallen

So the sentence is describing a completed event: the tile fell.

Also, cecidit comes from an important irregular-looking principal part:

• cado, cadere, cecidi, casum

The perfect stem is cecidi-, not something like cad-.

Yes. The Latin perfect often covers both meanings that English separates:

• simple past: fell
• present perfect: has fallen

Which English translation is best depends on context. In a narrative, fell is often the most natural.

Faber means craftsman, builder, workman, or artisan. In this context, it probably means something like builder or workman.

It is nominative singular, and it is the subject of dicit:

• faber dicit = the builder says

So the sentence shifts from what physically happened to what the builder claims about the structure.

Because Latin commonly uses indirect statement after verbs of saying, thinking, knowing, hearing, and so on.

Instead of saying:

• he says that the beam and arches remain strong

Latin usually says:

• he says the beam and arches to remain strong

That sounds odd in English, but it is normal Latin. The pattern is:

• verb of saying/thinking
• accusative subject
• infinitive

So here:

• dicit = he says
• trabem et fornices = the subjects of the reported statement, put into the accusative
• manere = the infinitive

This construction is often called the accusative-and-infinitive construction.

Yes, it is the subject of manere in sense, but in an indirect statement the subject is put into the accusative, not the nominative.

So:

• direct statement: trabs manet = the beam remains
• indirect statement after dicit: dicit trabem manere = he says that the beam remains

That is why you get trabem instead of trabs.

Because for many third-declension nouns, the nominative plural and accusative plural look the same.

The noun is:

• fornix, fornicis = arch, vault

Its plural forms are:

• nominative plural: fornices
• accusative plural: fornices

So in this sentence, fornices is accusative plural because it is also part of the subject of the indirect statement:

• dicit trabem et fornices ... manere

Even though the form looks the same as the nominative, its function here is accusative.

Firmos agrees with both trabem and fornices together.

A few things are happening at once:

1. trabem is feminine singular
2. fornices is masculine plural
3. Together they form a plural idea: the beam and the arches
4. When Latin uses one adjective for nouns of different genders, the masculine plural is the normal default if one of the nouns is masculine

So:

• not singular, because it describes more than one thing
• masculine plural, because the group includes masculine fornices

That is why firmos is correct.

Because Latin can use one adjective to describe multiple nouns together.

Instead of repeating the adjective for each noun separately, Latin often lets one plural adjective cover the whole group:

• trabem et fornices firmos

This means the beam and the arches, strong.

If Latin wanted to describe each noun separately, it could repeat adjectives, but that is unnecessary here. The shared adjective is more economical.

Manere is the present active infinitive of maneo.

• manent = they remain
• manere = to remain

In an indirect statement after dicit, Latin uses the infinitive, not a finite verb. So:

• direct: fornices manent
• indirect: dicit fornices manere

That is why manere appears here.

Because firmos is a predicate adjective connected with the accusative subject of the infinitive.

In an indirect statement:

• the subject goes into the accusative
• any adjective describing that subject also goes into the accusative

So:

• trabem et fornices = accusative subjects of manere
• firmos = accusative adjective agreeing with them

This is the same reason you would get:

• dicit puellam laetam esse = he says that the girl is happy

Here puellam and laetam are both accusative.

It has two main parts joined by sed:

1. Una tegula de tecto cecidit

   • a complete main clause
   • subject: una tegula
   • verb: cecidit
   • phrase of motion/source: de tecto

2. sed faber dicit trabem et fornices firmos manere

   • another main clause: faber dicit
   • followed by an indirect statement: trabem et fornices firmos manere

So the basic shape is:

• [Something happened], but [the builder says that something else is still true].

Latin word order is more flexible than English word order because case endings show grammatical function.

Still, the order here is natural and meaningful:

• Una tegula comes first, drawing attention to the single tile
• de tecto follows naturally with the idea of falling
• cecidit comes at the end of the clause, a common position for a verb
• in the second clause, faber dicit introduces the report
• trabem et fornices firmos manere then gives the content of what he says

So the word order is not random, but grammar does not depend on order as heavily as in English.