Magistra dicit hanc sententiam a Lucia penna pulchre scriptam esse.

Because after dicit, Latin often uses an indirect statement construction.

In English, we say:

• The teacher says that this sentence was written...

But in Latin, instead of using that plus a finite verb, Latin normally uses:

• an accusative noun as the subject of the reported statement
• plus an infinitive

So hanc sententiam is not the direct object in the ordinary sense of dicit. It is the subject of the infinitive scriptam esse inside the indirect statement.

In other words:

• Magistra dicit = the teacher says
• hanc sententiam ... scriptam esse = this sentence to have been written ...

That is why hanc sententiam is accusative.

Scriptam esse is the perfect passive infinitive of scribo.

Its parts are:

• scriptam = the perfect passive participle
• esse = to be

Together they mean:

• to have been written

Since this is in an indirect statement after dicit, Latin uses the infinitive instead of a finite verb such as scripta est.

So:

• scripta est = it was written
• scriptam esse = to have been written

The second form is the one needed in indirect statement.

Because scriptam must agree with hanc sententiam.

Sententiam is:

• feminine
• singular
• accusative

So the participle must also be:

• feminine
• singular
• accusative

That gives scriptam.

If the noun were masculine singular, you would get scriptum only if it were neuter; masculine would be scriptum? No—here it helps to remember the participle endings clearly:

• masculine accusative singular: scriptum
• feminine accusative singular: scriptam
• neuter accusative singular: scriptum

Since sententia is feminine, scriptam is correct.

Because this is a passive idea, and Lucia is the person doing the action.

In Latin, the personal agent with a passive verb is usually expressed by:

• a or ab
  • ablative

So:

• a Lucia = by Lucia

This is different from an instrument or means. A person who performs the action gets a/ab + ablative.

Compare:

• a Lucia = by Lucia
• penna = with a pen

So Latin distinguishes clearly between:

• the agent: the person responsible
• the instrument: the thing used

This is the ablative of means or ablative of instrument.

Latin often uses the plain ablative, with no preposition, to show the tool or means by which something is done.

So:

• penna = with a pen

No cum is needed here.

A useful contrast is:

• a Lucia = by Lucia, the agent
• penna = with a pen, the instrument

Latin usually uses:

• a/ab for a personal agent in a passive sentence
• simple ablative for an inanimate means or instrument

Pulchre is an adverb, and it modifies the verbal idea scriptam esse.

So it tells us how the sentence was written:

• pulchre = beautifully

Even though Latin word order is flexible, pulchre belongs with the writing action, not with Lucia or penna.

So the sense is:

• the sentence was beautifully written

not:

• the beautiful pen
• beautiful Lucia

If Latin wanted to describe the noun penna or Lucia, it would use an adjective agreeing with that noun, not the adverb pulchre.

Latin word order is much freer than English word order because Latin endings show the grammatical relationships.

English depends heavily on position:

• Lucia wrote the sentence
• The sentence wrote Lucia would mean something very different

Latin depends much more on case endings and verb forms. So in this sentence, you can identify the parts by grammar:

• Magistra = nominative, subject of dicit
• hanc sententiam = accusative, subject of the infinitive in indirect statement
• a Lucia = agent
• penna = instrument
• pulchre = adverb
• scriptam esse = perfect passive infinitive

The order chosen here is natural Latin, but not the only possible order.

It can be, but learners should know that sententia has a wider range of meanings than English sentence.

Common meanings include:

• opinion
• judgment
• idea
• thought
• maxim
• sentence

So in some contexts sententia might mean:

• an opinion
• a clever saying
• a thought

In this sentence, because it is something written and referred to with hanc, the meaning this sentence makes good sense.

A good clue is the verb dicit.

After verbs of saying, thinking, knowing, perceiving, and similar ideas, Latin often uses accusative + infinitive.

Here is the pattern:

• Magistra dicit = the teacher says
• then comes the reported content:
  • hanc sententiam ... scriptam esse

So when you see:

1. a verb like dicit
2. then an accusative noun
3. then an infinitive

you should strongly suspect an indirect statement.

That pattern is exactly what we have here.

Yes—that awkward literal version can actually help you see the structure.

A very literal unpacking is:

• Magistra = the teacher
• dicit = says
• hanc sententiam = this sentence
• a Lucia = by Lucia
• penna = with a pen
• pulchre = beautifully
• scriptam esse = to have been written

That is not good English, but it shows the Latin grammar clearly.

Once you see the structure, you can turn it into natural English much more easily.