Learn Hardcore Icelandic: Í bókasafninu er betra að vera þögull en hávær. - In the library it is better to be silent than loud.

Í bókasafninu literally focuses on being inside the building.
Á bókasafninu tends to mean at the library as an institution, an activity-place, not so much the physical interior.

In your sentence, either could be understood, but:

Í bókasafninu er betra að vera þögull en hávær.
Emphasis on how one should behave inside the library room.

If your teacher gave you í bókasafninu, stick with that here; it is completely natural and probably the more straightforward choice for this context.

Why does the sentence start with Í bókasafninu and not with the verb er?

Icelandic main clauses generally follow a verb-second (V2) rule: the finite verb (here: er) must be in second position in the clause.

That does not mean the verb has to be the first word. It means:

one constituent (here, the prepositional phrase Í bókasafninu) comes first,
then the finite verb er must immediately follow it.

So:

Í bókasafninu er betra… → [PP] + [V] + … (correct V2)
You could also say: Betra er að vera þögull… → [AdjP] + [V] + … (also V2)

Starting with Í bókasafninu puts the place in focus: In the library (as opposed to elsewhere), it is better to be quiet.

Why is it betra and not betri or betur?

All three are related, but they have different grammatical roles:

betri – comparative adjective, masculine/feminine nominative singular
betra – comparative adjective, neuter nominative/accusative singular
betur – comparative adverb, better in the sense of in a better way

Here, betra is an adjective agreeing in gender with an understood neuter subject.

The underlying structure is basically:

(Það) er betra að vera þögull en hávær.
It is better to be quiet than loud.

Það here is a dummy neuter subject (like English it in it is raining), so the adjective takes the neuter form betra. That is why we do not say betri or betur in this sentence.

What is the subject of er betra? There is no word like “it” in the sentence.

Grammatically, Icelandic usually has a dummy subject það in this kind of construction, just as English uses dummy it:

Það er betra að vera þögull en hávær.
It is better to be quiet than loud.

In your sentence, það is simply omitted because another element, Í bókasafninu, has been moved to the front for emphasis, and in such cases Icelandic can drop það:

Í bókasafninu er (það) betra að vera þögull en hávær.

You can think of the subject as an implicit neuter “it” referring to the whole idea að vera þögull en hávær.

Why do we need að in að vera þögull?

Að here is the normal infinitive marker, similar to to in English to be.

vera = be (bare infinitive form)
að vera = to be

In many constructions after adjectives like betra, Icelandic uses the infinitive with að:

Það er erfitt að læra íslensku. – It is hard to learn Icelandic.
Það er skemmtilegt að lesa bækur. – It is fun to read books.

So að vera þögull = to be quiet.

Why are the adjectives þögull and hávær in the masculine form?

They agree with an understood masculine “person”, not with bókasafninu.

The structure að vera þögull / hávær is shorthand for að vera (maður) þögull / hávær:

maður (person / one / you in general) is grammatically masculine, so the default agreement is masculine nominative singular:
- þögull (masc. nom. sg.) – quiet, silent
- hávær (masc. nom. sg.) – loud, noisy

You can see the same pattern when you specify the person:

Hann er þögull. – He is quiet.
Hún er þögul. – She is quiet. (feminine form)
Barnið er þögult. – The child is quiet. (neuter form)

In a general statement about how one should behave, Icelandic normally uses the masculine as the generic default, so þögull and hávær appear in that form.

What is the difference between þögull and similar words like hljóðlátur or rólegur?

They are all positive, but the nuances differ:

þögull
- Core idea: silent, not speaking.
- Focuses strongly on not talking.
- Can sometimes imply being unusually or suspiciously quiet, depending on context.
hljóðlátur
- Core idea: quiet, low-noise.
- Often about making little sound in general (talking, moving, objects, etc.).
- Very natural for library behaviour.
rólegur
- Core idea: calm, relaxed.
- More about mood or temperament than noise level.
- A rólegur person might still talk, just not in an agitated way.

In a library context:

að vera þögull = especially about not talking.
að vera hljóðlátur = about keeping overall noise low; often the most neutral word for “quiet” in places like libraries.

Why is en used here to mean than? Isn’t en usually but?

Yes, en can mean both but and than. The meaning depends on the structure:

As “but” (conjunction contrasting sentences/clauses):
- Ég vil koma, en ég hef ekki tíma.
  I want to come, but I don’t have time.
As “than” in comparisons:
- betri en – better than
- stærri en – bigger than
- Í bókasafninu er betra að vera þögull en hávær.
  …better to be quiet than loud.

In comparative constructions (with meira, betri/betra, stærri, etc.), en should be understood as “than”.

Can I say Betra er að vera þögull en hávær í bókasafninu instead? Is the meaning the same?

Yes, that is a perfectly correct alternative, and the meaning is essentially the same.

Betra er að vera þögull en hávær í bókasafninu.
[AdjP] + [V] + rest (still V2)

The differences are mainly in information structure / emphasis:

Í bókasafninu er betra…
Emphasises the place first: In the library, it is better…
Betra er að vera þögull… í bókasafninu.
Emphasises the evaluation first: It is better to be quiet… (in the library).

Both are natural; the first one highlights the setting more strongly.

How would the sentence change if I talk directly to someone, like “You should be quiet in the library”?

You would switch from an impersonal construction (it is better to…) to a more personal or obligational one. For example:

Þú átt að vera þögull í bókasafninu.
You ought to be quiet in the library.
Þú ættir að vera þögull í bókasafninu.
You should be quiet in the library. (a bit softer / more hypothetical)
Þú átt að vera hljóðlátur í bókasafninu.
You ought to be quiet (low-noise) in the library.

The original:

Í bókasafninu er betra að vera þögull en hávær.
is more like a general rule or piece of advice for people in general rather than a direct instruction to you.

Is there a verb for “to be quiet” instead of using vera þögull?

Yes, the verb þegja means roughly to be silent / to stop talking.

Geturðu þagað? – Can you be quiet / shut up?
Allir þögnuðu. – Everyone fell silent.

Difference in use:

vera þögull – describes a state: someone is (generally or currently) quiet.
þegja – an action or event: someone goes silent, stops speaking, or keeps silent.

In your sentence, we are describing the state or behaviour that is preferable in the library, so vera þögull is the natural choice.

How do you pronounce þögull and hávær?

Approximate pronunciations (in simple English-like notation):

þögull ≈ THUH-gutl
- þ like English th in think.
- ö is a mid front rounded vowel, somewhat like the vowel in British bird (without the “r”), or French eu in peur.
- gu here is close to guh.
- Final -ll in modern Icelandic is often a kind of tl or dl sound; many learners say -l at first, which is understood.
hávær ≈ HOW-vair
- há: á is like ow in now.
- v is a normal v sound.
- ær: æ like eye, and r is a tapped/rolled r. Together roughly vair / va-ir.

Precise Icelandic pronunciation is more detailed than this, but these approximations will make you clearly understood.