Learn Hardcore Latin: Post quietam noctem corpus discipulae non est triste, sed laborare vult et studere potest. - After a quiet night the female student's body is not sad, but it wants to work and is able to study.

The preposition post (“after”) governs the accusative case.
So whatever comes after post must be accusative: here, noctem (night), with quietam (“quiet”) agreeing with it.

So post quietam noctem = “after a quiet night,” with “night” as the object of the preposition post.

What are the roles of corpus and discipulae? Which one is the subject?

The subject is corpus (“body”).

corpus: nominative singular neuter, the grammatical subject of est, vult, and potest.
discipulae: genitive singular feminine, “of the student.”

Together they form a noun phrase:

corpus discipulae = “the body of the student” / “the student’s body.”

So the whole subject is “the student’s body.” Latin does not mark possession with ’s like English, but with the genitive case (discipulae).

Why is discipulae in the genitive and not discipula in the nominative?

If you wrote corpus discipula (both nominative), it would look like two separate subjects: “the body and the student,” which is not what is meant.

The genitive (discipulae) shows possession or close association: “the body of the student.”
So corpus discipulae clearly means “the student’s body,” not “the body and the student.”

Why is the adjective triste used, and what does it agree with?

Triste is the nominative singular neuter form of the adjective tristis, triste (“sad”).

It agrees with corpus, which is also neuter singular nominative.
Predicate adjectives in Latin must match the noun they describe in gender, number, and case.

So:

corpus (n. sg. nom.)
triste (n. sg. nom.)

This is why we have triste, not tristis (masc./fem.) or tristum (neuter accusative).

Could this sentence mean “the student is not sad,” or does it have to mean “the student’s body is not sad”?

Grammatically, it must mean “the student’s body is not sad.”

The clear subject is corpus discipulae (“the body of the student”).
Triste agrees with corpus, not directly with discipulae.

If you wanted to say “the student is not sad,” you would write something like:

Post quietam noctem discipula non est tristis.
(“After a quiet night, the student is not sad.”)

So the original sentence focuses specifically on the body being in a good state.

Why isn’t there a word for “it” before vult and potest?

Latin usually does not use subject pronouns like “he,” “she,” or “it” unless there is special emphasis or contrast.

The subject is already clear: corpus discipulae.
Once the subject is established, Latin simply continues with the verbs vult and potest, without repeating “it.”

So:

corpus discipulae non est triste, sed laborare vult et studere potest

literally: “the body of the student is not sad, but [it] wants to work and [it] is able to study,”
where “[it]” is understood from context, not written.

What kind of forms are laborare and studere, and how do they work with vult and potest?

Laborare and studere are present active infinitives:

laborare = “to work”
studere = “to study” / “to be eager for, to pursue studies”

With verbs like:

vult (“wants”)
potest (“is able, can”)

Latin uses a complementary infinitive:

laborare vult = “(it) wants to work”
studere potest = “(it) is able to study / can study”

This is very close to English: “wants to … / is able to …”

Why is there no ut in “laborare vult et studere potest”?

Verbs such as volo (“want”) and possum (“can, be able”) normally take a bare infinitive, not an ut-clause.

laborare vult – correctly “wants to work”
You would not say ut laboret vult for this meaning in normal prose.

Ut is used for other kinds of clauses, especially:

purpose clauses: venit ut laboret – “he came in order to work”
result clauses: tam fessus est ut laborare non possit – “he is so tired that he cannot work”

Here, vult and potest are just completed by an infinitive.

Why does the sentence start with Post quietam noctem instead of with the subject?

Latin word order is quite flexible and often used for emphasis or stylistic reasons, not strict grammar.

Putting Post quietam noctem first:

Sets the time frame right away: “After a quiet night…”
Gives a natural “scene setting” feel, common in Latin narrative and description.

You could also say:

Corpus discipulae non est triste post quietam noctem, sed laborare vult et studere potest.

This is grammatically fine, just a different emphasis. The meaning stays the same.

Why is triste used instead of tristis?

The adjective pattern is:

Masculine/Feminine nominative singular: tristis
Neuter nominative singular: triste

Since corpus is neuter, the adjective must also be neuter:

corpus triste = “a sad body” (neuter)
discipula tristis = “a sad (female) student” (feminine)

Using tristis with corpus would be a gender mismatch, so triste is the correct form.

Does studere need an object, and if so, what case would that object take?

Studere is a verb that typically takes a dative object in Latin:

studere litteris – “to study literature” / “to be devoted to letters”
studere linguae Latinae – “to study the Latin language” (literally “to be eager for the Latin language”)

In this sentence, studere has no explicit object:

studere potest – “(it) is able to study.”

The object is left understood (e.g. studies in general, schoolwork, etc.), which is natural and common in Latin when the context makes it obvious.