Magistra dicit discipulam diligentem esse, quia mendum cito corrigit.

It has three parts:

1. Magistra dicit = the main clause, the teacher says
2. discipulam diligentem esse = an indirect statement, reporting what the teacher says
3. quia mendum cito corrigit = a because-clause, giving the reason

So the structure is:

[The teacher says] [the student to be diligent] [because she corrects a mistake quickly].

That middle part sounds strange in English, but it is a very normal Latin pattern.

Because Latin often does not use a separate word equivalent to English that in reported statements.

Instead, after verbs like dicit, Latin commonly uses the accusative + infinitive construction:

• dicit discipulam diligentem esse

This is how Latin says:

• says that the student is diligent

So English uses that, but Latin usually switches to a different grammatical structure instead.

Because discipulam is the subject of the infinitive esse inside an indirect statement.

In Latin indirect statement, the subject goes into the accusative. So:

• direct statement: discipula diligens est = the student is diligent
• indirect statement after dicit: discipulam diligentem esse = that the student is diligent

So discipulam is not the direct object of dicit in the ordinary sense; it is the accusative subject of esse.

Because it agrees with discipulam.

Diligentem is describing the student, so it must match discipulam in:

• gender: feminine
• number: singular
• case: accusative

That is why Latin has:

• discipulam diligentem

not

• discipulam diligens

In the direct version, you would have:

• discipula diligens est

But once the subject changes to accusative in indirect statement, the adjective changes too:

• discipulam diligentem esse

Because in indirect statement Latin uses an infinitive, not a finite verb.

So the direct statement would be:

• discipula diligens est = the student is diligent

But after dicit, Latin changes est to the infinitive esse:

• dicit discipulam diligentem esse

This is one of the most important patterns in Latin syntax: after verbs of saying, thinking, knowing, hearing, and similar verbs, Latin often uses accusative + infinitive.

Its dictionary form is diligens.

This is a third-declension adjective, not a first/second-declension adjective like bonus, bona, bonum.

For diligens, the feminine accusative singular is:

• diligentem

So even though discipulam is a first-declension noun, the adjective does not have to look first-declension. It only has to agree with the noun in case, number, and gender.

That agreement here is:

• discipulam = feminine accusative singular
• diligentem = feminine accusative singular

Here mendum is the direct object of corrigit, so it is accusative singular.

It looks the same as the nominative because mendum is a neuter second-declension noun, and in Latin neuter nouns often have the same form in nominative and accusative.

So:

• nominative singular: mendum
• accusative singular: mendum

Its job in the sentence shows that it is accusative: the action corrigit is being done to the mistake.

Because Latin often leaves subject pronouns unstated when the verb ending already shows the person and number.

Both dicit and corrigit are third person singular:

• dicit = he/she/it says
• corrigit = he/she/it corrects

So Latin does not need to add ea every time. This is very normal.

English usually requires a subject pronoun, but Latin often does not.

Not from grammar alone.

Corrigit is just he/she/it corrects, so the subject is not explicitly stated. In context, many readers will naturally understand it as referring to the student, because that makes sense with diligentem: she is diligent because she corrects a mistake quickly.

But strictly speaking, without more context, the grammar does not force that reading. It could in theory refer to the teacher.

If Latin wanted to make it fully explicit, it could repeat the noun:

• quia discipula mendum cito corrigit = because the student corrects a mistake quickly
• quia magistra mendum cito corrigit = because the teacher corrects a mistake quickly

Because quia introduces a regular subordinate clause of reason:

• quia mendum cito corrigit = because she corrects a mistake quickly

That clause has its own normal finite verb, corrigit.

By contrast, esse appears because discipulam diligentem esse is an indirect statement after dicit.

So the sentence contains two different constructions:

• indirect statement: discipulam diligentem esse
• causal clause: quia mendum cito corrigit

Latin word order is much freer than English word order.

This sentence puts words in a very natural and readable order:

• Magistra dicit
• discipulam diligentem esse
• quia mendum cito corrigit

But Latin could rearrange some parts without changing the basic meaning, for example:

• Magistra discipulam diligentem esse dicit
• Magistra dicit disciplinam esse diligentem
• quia cito mendum corrigit

The endings, not the position alone, usually show each word’s role.

That said, word order can affect emphasis. For example, placing cito right before corrigit gives a neat emphasis to the manner: she corrects quickly.

It would be:

• Discipula diligens est.

That means:

• The student is diligent.

Then, after a verb like dicit, Latin turns that direct statement into indirect statement:

• discipula → discipulam
• diligens → diligentem
• est → esse

So:

• Discipula diligens est. becomes
• Magistra dicit discipulam diligentem esse.

This is a very useful transformation to practice, because Latin does it all the time.