Magistra discipulam monet ne codicem suum domi relinquat.

Because magistra is the subject of the main verb monet, and discipulam is the direct object of that verb.

• magistra = the teacher → nominative singular
• discipulam = the female student / pupil → accusative singular

So the structure is:

• Magistra = the one doing the warning
• discipulam = the one being warned

Latin often shows these roles by case endings rather than by word order.

Because moneō normally takes a direct object in the accusative for the person warned or advised.

So:

• discipulam monet = she warns/advises the student
• not discipulae monet

This is different from some English expressions where we might think of to someone. In Latin, with moneō, the person is usually treated as a direct object.

Monet is the 3rd person singular present active indicative of moneō, monēre.

It can mean things like:

• warns
• advises
• reminds

In this sentence, it introduces a warning or instruction. After moneō, Latin can use a clause with ut or ne plus the subjunctive to express what someone is urged to do or not do.

So here the idea is:

• The teacher warns/advises the student not to leave...

Here ne introduces a negative indirect command after monet.

A very common pattern is:

• monet ut ... = warns/advises that ... should
• monet ne ... = warns/advises that ... should not

So ne here means something like:

• that ... not
• or more naturally in English, simply not

It is not the same as the ordinary standalone word for not in every situation. In this construction, ne is the normal word used for a negative command or warning inside a subordinate clause.

Because it is part of an indirect command after monet.

After verbs like warn, advise, urge, persuade, Latin often uses:

• ut
  • subjunctive for a positive command
• ne
  • subjunctive for a negative command

So:

• monet ne ... relinquat = she warns her not to leave...

The subjunctive is required by the construction, not because the action is doubtful.

The present subjunctive is the normal tense here because the warning is about an action that is to happen at the same time as or after the warning.

The teacher is warning the student now about what she should not do.

So:

• monet = present
• relinquat = present subjunctive in the subordinate clause

This is the usual sequence for a warning about a present/future action.

The understood subject of relinquat is discipulam.

In English we might say:

• The teacher warns the student not to leave her book at home.

In Latin, the student is the object of monet, but she is also the understood subject of the subordinate verb relinquat.

So the sense is:

• The teacher warns the student that she should not leave...

where she = the student.

Because suus, sua, suum is the reflexive possessive adjective. It refers back to the subject of its own clause.

In the clause:

• ne codicem suum domi relinquat

the understood subject of relinquat is the student, so suum means her own and refers to the student.

So:

• suum = her own (the student’s own notebook/book)

If Latin used eius instead, it would usually mean his/her referring to someone else, not to the subject of that clause.

That is why suum is the natural choice here.

Suum agrees with codicem.

Possessive adjectives in Latin agree with the thing possessed, not with the possessor.

So:

• codicem is masculine singular accusative
• therefore suum is also masculine singular accusative

Even though the owner is the female student, the adjective must match codicem, not discipulam.

Codicem is the accusative singular of codex, codicis.

It is accusative because it is the direct object of relinquat:

• relinquat codicem = leave the book/notebook

So inside the subordinate clause:

• the student is the understood subject of relinquat
• codicem is the thing she might leave behind

Codex originally means something like a book, manuscript, or writing tablet/booklet. In many learner-friendly contexts it is often translated as:

• book
• notebook
• textbook

Exactly which English word is best depends on context. Grammatically, though, it behaves simply as a masculine third-declension noun:

• nominative singular: codex
• accusative singular: codicem

Because domi is the locative form meaning at home.

A few Latin nouns have a special locative form for place where, and domus is one of the most common examples.

So:

• domi = at home
• in domo can also mean in the house/home, but domi is a very standard idiomatic way to say at home

In this sentence, domi is exactly the sort of form learners are expected to recognize as a fixed, common expression.

It looks the same, but here its function is best understood as part of an indirect command after monet.

You may have learned:

• ut
  • subjunctive = purpose clause, in order that
• ne
  • subjunctive = negative purpose clause, in order that ... not

But after verbs like warn, advise, persuade, or order, ut/ne + subjunctive is usually better explained as a noun clause of command rather than a purpose clause.

So in this sentence, the best explanation is:

• monet ne relinquat = warns her not to leave

not primarily:

• warns her in order that she may not leave

The sentence is arranged like this:

• Magistra = subject
• discipulam = object
• monet = main verb
• ne codicem suum domi relinquat = subordinate clause

Latin word order is much more flexible than English word order because case endings carry a lot of grammatical information. Still, this sentence is quite natural:

• main statement first
• then the ne clause explaining the content of the warning

Also, Latin often likes to place verbs toward the end of their clause, which is why relinquat comes at the end of the subordinate clause.

That is close to the structure of the Latin, but it is not natural English.

A more literal grammatical unpacking would be something like:

• The teacher warns the student that she should not leave her book at home

But idiomatic English normally says:

• The teacher warns the student not to leave her book at home

So the Latin uses ne + subjunctive, while English usually prefers an infinitive after warn in this kind of sentence.

It is active.

Relinquat comes from relinquō, relinquere, meaning leave behind or abandon.

Formally it is:

• 3rd person singular
• present subjunctive
• active

So it means:

• she may leave
• she should leave

But in this sentence, because of ne and monet, the actual sense is:

• that she should not leave

Because this is not just an ordinary negative statement. It is a negative command/warning inside a subordinate clause.

Latin normally uses:

• nōn for ordinary negation in statements
• ne for negative commands and similar subjunctive clauses

So:

• nōn relinquit = she does not leave
• ne relinquat = that she not leave / not to leave

That is why ne is correct here.

Normally, no. In this sentence suum naturally refers to the understood subject of relinquat, which is the student.

So the meaning is:

• the student’s own book/notebook

If Latin wanted to say that it was the teacher’s book, it would normally need a different wording, because suus points back reflexively within its own clause.

A learner should especially notice these:

1. Case endings

   • magistra = nominative subject
   • discipulam = accusative object
   • codicem = accusative object of relinquat

2. Verb + indirect command

   • monet ne ... relinquat
   • after moneō, Latin often uses ut/ne + subjunctive

3. Subjunctive mood

   • relinquat is subjunctive because it is in an indirect command

4. Reflexive possessive

   • suum refers to the student, the understood subject of relinquat

5. Locative

   • domi = at home

So this is a very useful sentence because it combines several important intermediate Latin features in one short example.