Imperium sine iustitia firmum manere non potest.

Because sine is a preposition that takes the ablative. So sine iustitia means without justice.

A native English speaker often expects a word-for-word match with English, but in Latin prepositions regularly control a specific case. Here:

• sine = without
• iustitia = ablative singular of iustitia, iustitiae

So the phrase is grammatically fixed as sine + ablative.

Because it agrees with imperium.

Imperium is:

• neuter
• singular
• nominative

So the adjective describing it must also be:

• neuter
• singular
• nominative

That gives firmum.

Even though in English we might say firm without changing its form, Latin adjectives must match the noun they describe in gender, number, and case.

Because it depends on potest.

Latin uses possum the same way English uses can or be able: it is followed by an infinitive.

So:

• potest manere = is able to remain / can remain
• non potest manere = cannot remain

Here manere is the complementary infinitive completing the meaning of potest.

The subject is imperium.

It is in the nominative singular, and potest is also third person singular, so they match:

• imperium = subject
• potest = is able, singular
• firmum = predicate adjective describing imperium
• manere = infinitive, to remain

So the core structure is:

Imperium ... firmum manere non potest
= Power / an empire cannot remain firm

Because manere means to remain, stay, continue, not simply to be.

That adds an important idea:

• esse firmum would mean to be firm
• firmum manere means to remain firm

So the sentence is not merely saying that power without justice is not firm; it says it cannot stay firm or cannot continue to be firm.

Because non negates the verbal idea: cannot remain.

In this sentence, non potest is the natural way to say is not able / cannot.

Latin word order is flexible, but this placement is very normal:

• non potest = cannot

So Imperium ... firmum manere non potest means Power ... cannot remain firm.

Yes, but not in a way that changes the basic meaning.

Latin word order is much freer than English because case endings show each word’s function. A straightforward grammatical analysis is still clear even when the order differs from English.

Here the order does a few useful things:

• Imperium comes first, giving prominence to the main topic.
• sine iustitia sits in the middle, adding the important condition without justice.
• firmum manere non potest saves the main verbal idea for the end: cannot remain firm.

An English rearrangement closer to the Latin order might be:

Power, without justice, firm to remain cannot.

That sounds unnatural in English, but it shows how Latin can move elements around for emphasis.

It can mean several related things, depending on context:

• power
• rule
• command
• government
• empire

In this sentence, it is probably being used in a broad political or moral sense, something like political power or state power.

A learner should know that many Latin nouns have a range of meanings, and the best English equivalent depends on context.

It is a predicate adjective with manere.

That means it is not simply attached to the noun inside a noun phrase, as in firmum imperium = a firm empire. Instead, it describes the subject through the verb:

• imperium firmum manet = power remains firm
• imperium firmum manere potest = power can remain firm

So firmum tells us the state or condition in which imperium remains.

Yes:

• Imperium

  • noun
  • nominative singular neuter
  • from imperium, imperii
  • subject of the sentence

• sine

  • preposition
  • takes the ablative
  • means without

• iustitia

  • noun
  • ablative singular feminine
  • from iustitia, iustitiae
  • object of sine

• firmum

  • adjective
  • nominative singular neuter
  • from firmus, -a, -um
  • agrees with imperium

• manere

  • present active infinitive
  • from maneo, manere
  • means to remain

• non

  • adverb
  • negates potest

• potest

  • verb
  • third person singular present active indicative
  • from possum, posse
  • means is able, can

Yes. Because Latin relies on inflection, several word orders would still express essentially the same idea.

For example:

• Imperium non potest sine iustitia firmum manere.
• Sine iustitia imperium firmum manere non potest.
• Firmum imperium sine iustitia manere non potest.
  This last one is a little different in nuance, because firmum imperium more strongly groups firm with imperium at the start.

The exact emphasis may shift, but the core grammar remains understandable because the forms show the relationships.

Because grammatical number depends on the form of the noun, not on how large the thing is in real life.

Imperium is a singular noun, so the verb is singular:

• imperium ... potest

Even if the idea is something vast, like an empire or a government, Latin still treats it grammatically as one thing here.

A useful way to see it is:

subject + prepositional phrase + predicate adjective + infinitive + negated modal verb

More specifically:

• Imperium = subject
• sine iustitia = prepositional phrase
• firmum = predicate adjective
• manere = infinitive
• non potest = finite verb phrase

So the backbone is:

Imperium firmum manere non potest
= Power cannot remain firm

with sine iustitia inserted to explain the condition: without justice.