Si culpa gravis est, poena quoque gravis est.

Si means if and introduces the condition.

So the sentence has two parts:

• Si culpa gravis est = if the guilt/fault is serious
• poena quoque gravis est = the punishment is also serious

This is a very standard Latin conditional pattern: si + a verb in the indicative.

Both culpa and poena are nominative singular.

They are nominative because each is the subject of its clause:

• culpa gravis est = the fault is serious
• poena gravis est = the punishment is serious

So each clause has its own subject in the nominative.

Because gravis is an adjective that must agree with the noun it describes in gender, number, and case.

Both culpa and poena are:

• feminine
• singular
• nominative

So the adjective is gravis in both places.

This is a good example of adjective agreement in Latin.

Gravis is a third-declension adjective.

Its nominative singular forms are:

• masculine: gravis
• feminine: gravis
• neuter: grave

So here, since culpa and poena are feminine singular nominative, gravis is the correct form.

Yes, Latin can sometimes leave out est when the meaning is clear, especially in short statements.

So you might also see:

• Si culpa gravis, poena quoque gravis.

But in your sentence, est is included in both clauses. That makes the structure very clear and balanced:

• culpa gravis est
• poena quoque gravis est

For a learner, this full version is especially helpful.

Quoque means also, too, or likewise.

Here it adds the idea that the second statement matches the first:

• if the fault is serious,
• the punishment is also serious.

So quoque connects the two ideas logically.

This is very normal in Latin.

Quoque usually comes after the word it emphasizes. So:

• poena quoque = the punishment too / the punishment also

That position is more natural in Latin than putting quoque before the word.

So a learner should get used to quoque often following the word it belongs with.

Primarily it goes with poena, because it follows that word:

• poena quoque = the punishment too

But in sense, it helps connect the whole second clause with the first. So the meaning is effectively:

• the punishment too is serious
• or more naturally in English, the punishment is also serious

So grammatically it is attached closely to poena, but logically it links the two statements.

Because classical Latin has no articles.

So Latin does not normally have separate words for:

• the
• a / an

That means culpa can mean fault, a fault, or the fault, depending on context. The same is true for poena.

English has to choose an article, but Latin usually does not state one.

No, Latin word order is much more flexible than English word order because the endings show the grammar.

This sentence is written in a very neat, balanced order:

• Si culpa gravis est, poena quoque gravis est.

That arrangement makes the parallelism easy to see:

• culpa ... gravis est
• poena quoque ... gravis est

Other word orders are possible, but this one is clear and elegant.

This is a simple present condition.

Both verbs are present indicative:

• si ... est
• ... est

It expresses a general idea or principle:

• if the fault is serious, the punishment is also serious

It is not a contrary-to-fact condition, and it is not especially hypothetical. It sounds like a general rule.

It depends on context.

Culpa can mean things like:

• fault
• blame
• guilt

In this sentence, the exact English choice depends on what meaning was given to the learner. Grammatically, nothing changes: culpa is the subject, and gravis describes it.

So even if translations vary a little, the Latin structure stays the same.

It is made of two linked clauses:

1. Si culpa gravis est

   • si = if
   • culpa = subject
   • gravis = predicate adjective
   • est = is

2. poena quoque gravis est

   • poena = subject
   • quoque = also
   • gravis = predicate adjective
   • est = is

So in both clauses, the pattern is basically:

• subject + adjective + est

That repeated structure makes the sentence easy to parse and nicely symmetrical.