Magister dicit discipulos non semper intellegere, sed conari debere.

After dicit, Latin is using an indirect statement construction, often called the accusative-and-infinitive construction.

Instead of saying that the students do not always understand, Latin says, more literally:

• the teacher says
• the students → in the accusative
• to not always understand → with an infinitive

So:

• Magister dicit discipulos non semper intellegere
• literally: The teacher says the students not always to understand
• natural English: The teacher says that the students do not always understand

The same pattern continues in the second half of the sentence.

Because in an indirect statement, the subject of the reported statement goes into the accusative.

So although discipulos is the one doing the understanding and trying, it is not the subject of the main verb dicit. The subject of dicit is magister.

Think of it like this:

• main statement: Magister dicit = The teacher says
• reported statement: discipulos ... intellegere ... debere = that the students ... understand ... ought

In normal direct speech, you would expect:

• discipuli non semper intellegunt

But after dicit, Latin changes that to:

• discipulos non semper intellegere

So discipulos is the logical subject of the infinitives, but grammatically it is accusative because of the indirect statement construction.

Because indirect statement in Latin uses an infinitive instead of a finite verb.

So where English says:

• The teacher says that the students do not always understand

Latin says:

• Magister dicit discipulos non semper intellegere

Here intellegere is the infinitive that carries the meaning of understand inside the reported statement.

In the second half:

• sed conari debere

the main infinitive of that part is debere, and conari depends on it as a complementary infinitive.

So the structure is roughly:

• dicit
  • discipulos ... intellegere
  • sed ... debere

In smoother English, we do not usually say to ought to try, but that is close to the literal Latin structure. We translate it naturally as:

• but that they ought to try or
• but ought to try

Debere means to owe, and from that it commonly develops the sense to have to, to ought to, or to should.

It often takes another infinitive with it. Here that infinitive is conari.

So:

• conari = to try
• debere = to ought / to have to
• conari debere = to ought to try

The subject of both infinitives is still discipulos, even though it is not repeated.

So the second half means:

• but that the students ought to try

Conari is a deponent verb.

That means:

• it has passive-looking forms
• but it has an active meaning

So although conari looks like a passive infinitive in form, it actually means:

• to try
• to attempt

This is something English speakers often notice because it looks unusual at first. It is perfectly normal Latin.

Some common deponent verbs are:

• conari = to try
• loqui = to speak
• sequi = to follow

So there is nothing passive in meaning here.

Non semper means not always.

So:

• discipulos non semper intellegere = that the students do not always understand

This is not the same as saying:

• they never understand or
• they always fail to understand

It means that sometimes they do understand, and sometimes they do not.

English speakers sometimes wonder about the scope of the negation. Here the natural sense is simply:

• not always

Because Latin usually does not use a separate word equivalent to English that in this kind of sentence.

English says:

• The teacher says that the students do not always understand

Latin normally expresses this by using the accusative-and-infinitive construction instead:

• Magister dicit discipulos non semper intellegere

So the idea of English that is built into the construction itself. You do not need a separate word for it.

It can mean any of those, depending on context.

Common possibilities are:

• must
• have to
• should
• ought to

Here, because the sentence contrasts failure with effort, the softer sense is probably best:

• ought to try or
• should try

If the speaker were being stricter, it could also be understood more strongly as:

• must try

So context decides how strong debere feels.

Grammatically, conari by itself means simply to try or to make an effort.

So the Latin as written most directly says:

• the students do not always understand, but they ought to try

However, because understanding has just been mentioned, English readers may naturally feel that the implied idea is:

• they ought to try to understand

That is a possible sense from context, but it is not stated explicitly in the Latin.

If Latin wanted to say that more explicitly, it could use something like:

• intellegere conari = to try to understand

Sed means but, and it marks a contrast.

The contrast is between:

• not always understanding and
• still having the duty to try

So the sentence is not merely listing two facts. It is setting them against each other:

• the students may not always understand,
• but they should still make the effort.

That is why sed works better than a simple and.

Yes. Discipulos is understood as the subject of both infinitive phrases.

So the sentence is structured like this:

• Magister dicit
  • discipulos non semper intellegere
  • sed conari debere

Expanded in English:

• The teacher says that the students do not always understand, but that the students ought to try

Latin does not need to repeat discipulos in the second part, because it is already understood from the first part.