Mercator iustus esse non dicitur, quia pretium nimium petit.

Because after a verb of saying, Latin often uses an indirect statement, and the verb inside that statement goes into the infinitive.

So:

• est = is
• esse = to be

Here Latin is not saying the merchant is just as a direct statement. It is saying the merchant is said to be just / not just. That is why esse appears.

Dicitur is the passive form of dicit, so it means is said.

Latin very commonly uses this passive pattern with verbs of saying:

• active: they say that the merchant is just
• passive: the merchant is said to be just

So Mercator iustus esse non dicitur literally means The merchant is not said to be just.

In smoother English, that can also come out as The merchant is not considered just.

A natural active version would be:

Mercatorem iustum esse non dicunt, quia pretium nimium petit.

or with an expressed subject:

Aliqui mercatorem iustum esse non dicunt, quia pretium nimium petit.

That means They do not say that the merchant is just, because he asks too much for the price.

This helps you see the passive transformation:

• active: mercatorem iustum esse
• passive: mercator iustus esse dicitur

Because in the passive version, the person being spoken about becomes the subject of the sentence.

Compare:

• active: mercatorem iustum esse dicunt

  • mercatorem = accusative
  • iustum = accusative, agreeing with mercatorem

• passive: mercator iustus esse dicitur

  • mercator = nominative
  • iustus = nominative, agreeing with mercator

So iustus is a predicate adjective describing mercator, and it matches it in case, number, and gender.

Pretium is accusative singular neuter.

Here it is the direct object of petit. The phrase pretium petere means to ask a price or to demand a price.

So:

• petit = he asks / seeks / demands
• pretium petit = he asks a price

In context, it means he asks too high a price or he charges too much.

In this sentence, nimium is best understood adverbially, meaning too much.

So the sense is:

• pretium nimium petit = he asks too much as a price
  or more naturally, he asks too high a price

A learner may notice that nimium has a form that could match pretium, and that is a reasonable thing to wonder about. But here the main idea is not an excessive price as a noun phrase; it is that he asks too much.

In practice, the English meaning ends up very similar either way.

Petit is the 3rd person singular present active indicative of peto.

Peto can mean several things depending on context, such as:

• seek
• aim at
• request
• ask for
• demand

With pretium, it means ask a price or demand a price.

So here petit is not just looks for; it means something like charges or asks for.

Quia means because and introduces a causal clause.

So the structure is:

• main clause: Mercator iustus esse non dicitur
• reason clause: quia pretium nimium petit

The second clause explains why the merchant is not called or regarded as just.

Because non normally comes just before the word or idea it is negating.

Here it negates dicitur:

• non dicitur = is not said

So the sentence means that the merchant is not said to be just.

Latin word order is flexible, but this placement is very natural and clear.

Yes, Latin could say that, and it would mean something like The merchant is not called/considered just.

But there is a slight difference in feel:

• mercator iustus esse non dicitur = the merchant is not said to be just
• mercator iustus non dicitur = the merchant is not called just

In English those are very close. In Latin, the version with esse makes the usual reported statement pattern especially clear.