Puella librum non in mensa, sed in scrinio relinquit, quia bibliotheca quietior est cum omnia ordine servantur.

Because librum is the direct object of relinquit.

• relinquit = leaves
• The thing being left is the book
• In Latin, a direct object usually goes in the accusative

So:

• puella = the girl (subject, nominative)
• librum = the book (direct object, accusative)

That is why you see librum, not liber.

Because here in means in/on in a location sense, not movement toward a place.

Latin uses:

• in + ablative = in/on somewhere
• in + accusative = into / onto somewhere

So:

• in mensa = on the table / in the table area, with mensa in the ablative
• in scrinio = in the desk / in the writing case / in the cabinet, with scrinio in the ablative

The sentence is describing where the book is left, not motion into the place, so the ablative is used.

Non ... sed ... means not ... but ...

It creates a contrast:

• non in mensa = not on the table
• sed in scrinio = but in the desk/cabinet

This is a very common Latin pattern. It works much like English:

• not here, but there
• not X, but Y

So the sentence is emphasizing the correct location by contrasting it with another one.

Because relinquit is the 3rd person singular present active indicative of relinquere.

Breakdown:

• relinqu- = verb stem
• -it = he/she/it in the present tense for many 3rd-conjugation verbs

So relinquit means:

• she leaves
• or he leaves, depending on the subject

Since the subject here is puella, it means the girl leaves.

Latin often uses the present tense in a straightforward way just like English does.

Because the ending of the verb already tells you the person and number.

In relinquit, the ending -it shows:

• 3rd person singular
• so: he/she/it leaves

Then the noun puella makes it clear who that she is.

Latin often does this:

• Puella legit. = The girl reads.
• No separate word for she is necessary.

A pronoun like ea could be added, but it is usually unnecessary unless you want emphasis or contrast.

Quietior is the comparative form of quietus, -a, -um, meaning quiet.

So:

• quieta = quiet
• quietior = quieter

It agrees with bibliotheca, which is feminine singular, but comparative adjectives in Latin often use the same nominative singular form -ior for both masculine and feminine.

So:

• bibliotheca quietior est = the library is quieter

This does not always need an explicit than phrase in Latin. Sometimes the comparison is simply understood from context.

Because bibliotheca is the subject of est.

In the clause:

• bibliotheca quietior est

the structure is:

• bibliotheca = the library
• quietior = quieter
• est = is

So bibliotheca is in the nominative because it is the thing being described.

This is similar to English the library is quieter, where the library is the subject.

Quia means because.

It introduces a clause giving the reason:

• quia bibliotheca quietior est ...
• because the library is quieter ...

So the first part says what the girl does, and the quia clause explains why she does it.

This is a very common way to introduce a reason in Latin.

No. Here cum means when, not with.

Latin cum can have different meanings depending on context:

• cum
  • ablative pronoun/noun = with
• cum introducing a clause = often when, since, or although

In this sentence:

• cum omnia ordine servantur

it introduces a clause, so it means something like:

• when everything is kept in order

This is a temporal or general-condition kind of cum.

Because omnia means all things or everything.

It is the neuter plural form of omnis, omne.

Here it functions as the subject of servantur:

• omnia = all things / everything
• servantur = are kept / are preserved

Latin often uses the neuter plural to refer to things in a general way.

So omnia servantur literally means all things are kept, which in smoother English becomes everything is kept.

Because the sentence is focusing on the state of the things, not on who is doing the action.

• servant = they keep
• servantur = they are kept

So:

• cum omnia ordine servantur = when everything is kept in order

This is natural in both Latin and English. The agent is not important here; the important idea is that things are maintained neatly.

Ordine is in the ablative singular of ordo, ordinis, meaning order.

Here it is used in an idiomatic phrase:

• ordine = in order, orderly, in proper arrangement

So:

• omnia ordine servantur = everything is kept in order

This is an example of the ablative being used adverbially, expressing the manner or condition in which something is done.

Because Latin relies much more on case endings than on word order to show grammatical relationships.

For example:

• puella is nominative, so it is the subject
• librum is accusative, so it is the direct object
• mensa, scrinio, ordine are ablative in their phrases

Since the endings already show the roles, Latin has more freedom to arrange words for:

• emphasis
• contrast
• style
• rhythm

In this sentence, the placement of non in mensa, sed in scrinio highlights the contrast strongly.

English depends much more on word order, so we cannot rearrange things as freely.

Yes. In Latin, in with the ablative can mean either in or on, depending on the noun and the situation.

So:

• in mensa can naturally mean on the table
• in scrinio can mean in the desk, in the box, or in the cabinet

Latin does not always distinguish in and on as strictly as English does. The context tells you which wording sounds best in translation.

Not exactly.

Scrinium can refer to a place or container for keeping writings or documents, such as:

• a desk
• a writing case
• a cabinet
• a box for papers

So the exact English word can vary with context. In a beginner sentence, desk or cabinet is often a reasonable translation, but the core idea is a place where written things are stored.

A helpful breakdown is:

• Puella librum relinquit = The girl leaves the book
• non in mensa, sed in scrinio = not on the table, but in the desk/cabinet
• quia bibliotheca quietior est = because the library is quieter
• cum omnia ordine servantur = when everything is kept in order

So the sentence has:

1. a main clause
2. a contrast inside that clause
3. a quia clause giving the reason
4. a cum clause adding a circumstance to that reason

That kind of layering is very common in Latin prose.