Labor perpetuus difficilis est.

The subject is labor.

It is in the nominative singular, which is the case Latin normally uses for the subject of a sentence. So labor is the thing being talked about.

Labor is nominative singular.

A learner often notices that labor looks like an English word, but in Latin it is a third-declension noun. Its dictionary form is usually given as labor, laboris. The -or form here is the nominative singular.

In this sentence, that makes sense because it is the subject.

They do two slightly different jobs.

• perpetuus describes labor directly: perpetual work
• difficilis is linked to labor through est: work is difficult

So you can think of the structure like this:

• labor perpetuus = perpetual work
• difficilis est = is difficult

Together: Perpetual work is difficult.

Because they belong to different adjective patterns.

• perpetuus is a first/second-declension adjective
• difficilis is a third-declension adjective

Even though their endings are different, they still agree with labor in:

• gender: masculine
• number: singular
• case: nominative

So the different endings do not mean they disagree. They are just following different declensional patterns.

Because it is a predicate adjective.

After a form of esse (to be), Latin often uses an adjective in the nominative to describe the subject. Since labor is nominative singular, difficilis is nominative singular too.

This is the same basic idea as in English:

• The work is difficult

Here difficult describes the subject work, and Latin shows that relationship by using the nominative.

Est is the third-person singular present indicative active of esse, meaning to be.

So est means:

• he/she/it is

In this sentence, it means is, because the subject labor is singular:

• labor ... est = work ... is

Because Latin word order is much more flexible than English word order.

Putting the verb at the end is very common in Latin, especially in simple statements. So:

• Labor perpetuus difficilis est

is perfectly normal Latin.

English usually requires a stricter order:

• Perpetual work is difficult

Latin can move words around more freely because endings show their grammatical role.

Yes, often they could.

For example, Latin could also say:

• Perpetuus labor difficilis est

That would still mean basically the same thing. The difference would mainly be one of emphasis or style, not core meaning.

Latin uses word order more for nuance than for basic grammar.

You know because of agreement.

Perpetuus is:

• masculine
• singular
• nominative

And labor is also:

• masculine
• singular
• nominative

So they match. Since there is no other noun here for it to agree with, perpetuus must describe labor.

Yes, that is a very helpful way to read it.

You can divide the sentence like this:

• labor perpetuus = the subject phrase
• difficilis est = what is being said about the subject

So the sentence structure is:

• [subject] + [predicate]

More specifically:

• [labor perpetuus] + [difficilis est]

That is a natural way to understand the grammar.

Because Latin has no articles.

Latin does not have words exactly like English the or a/an. So labor can mean:

• work
• the work
• a work

Which one sounds best depends on the context. In a sentence like this, English usually translates it without an article or with the, depending on style.

Here is the breakdown:

• labor: third-declension noun
• perpetuus: first/second-declension adjective
• difficilis: third-declension adjective
• est: form of the irregular verb esse

This is a very common thing in Latin: words can belong to different declensions but still fit together grammatically through agreement.

A common reconstructed Classical pronunciation would be approximately:

LAH-bor per-PET-woo-us dif-fee-KI-lis est

A few helpful points:

• c is always hard in Classical Latin, but there is no c here
• v in Classical Latin sounds like w, so in perpetuus the u/v sound is like w
• est is pronounced with a clear e and st

A more detailed approximation:

• labor = LAH-bor
• perpetuus = per-PET-woo-us
• difficilis = dif-fee-KI-lis
• est = est

The difference is:

• perpetuus is an attributive adjective
• difficilis is a predicate adjective

That means:

• attributive adjective: directly attached to the noun
  
  • labor perpetuus = perpetual work
• predicate adjective: linked to the noun by est
  • labor ... difficilis est = work ... is difficult

This distinction is very useful when reading Latin sentences with esse.