Learn Hardcore Icelandic: Það er ekki hægt að læra allt á einum degi. - It is not possible to learn everything in one day.

There is no specific thing that „það“ stands for; it’s just filling the subject slot required by the verb „er“ (is). This is very common in Icelandic with expressions about weather, time, and possibility:

Það rignir. – It is raining.
Það er kalt. – It is cold.
Það er erfitt að læra íslensku. – It is hard to learn Icelandic.

So „Það er ekki hægt…“ literally mirrors English “It is not possible…” with a dummy „það“.

What exactly is „hægt“ and how does it work in this sentence?

„Hægt“ here means “possible” and functions as a kind of impersonal adjective/adverb.

Historically, „hægt“ is the neuter singular form of the adjective „hægur“ (slow, easy), but in modern Icelandic this form is used very widely in expressions of possibility and is felt almost like an adverb meaning “possible / possibly”:

Það er hægt að gera þetta. – It is possible to do this.
Er hægt að fá vatn? – Is it possible to get water? / Can I get some water?
Það er ekki hægt að læra allt á einum degi. – It is not possible to learn everything in one day.

In this construction, „hægt“ does not agree with any obvious noun; it just appears in the neuter form with dummy „það“ and an „að + infinitive“ clause after it.

Why do we say „að læra“? What is the role of „að“ before a verb?

Here „að“ is the infinitive marker, like “to” in English “to learn”.

læra = to learn (bare infinitive)
að læra = to learn (infinitive with marker „að“)

In constructions like „hægt að…“, „erfiðt að…“, „gaman að…“, you almost always follow them with „að + infinitive“:

Það er erfitt að læra íslensku. – It is hard to learn Icelandic.
Það er gaman að lesa. – It is fun to read.
Það er ekki hægt að læra allt á einum degi. – It is not possible to learn everything in one day.

So the pattern is: Það er [adjective] að [verb in infinitive].

Why is the word order „er ekki hægt“ and not „er hægt ekki“?

Icelandic word order in simple main clauses is often described as V2 (verb in 2nd position), but adverbs like „ekki“ usually come after the verb and before many other elements.

In a neutral sentence with dummy subject „það“, the pattern is:

Subject: Það
Verb: er
Negation/adverb: ekki
Predicate complement: hægt
Infinitive clause: að læra allt á einum degi

So we get:

Það er ekki hægt að læra allt á einum degi.

Putting „ekki“ after „hægt“ („Það er hægt ekki…“) would be ungrammatical in standard Icelandic.

Why is it „allt“ and not some other form of “all”?

„Allt“ is the neuter singular form of „allur“ meaning “all / everything”.

Here it is used on its own as a pronoun, not modifying a noun. It means “everything” in a general sense:

Ég skil allt. – I understand everything.
Þú getur ekki lært allt. – You cannot learn everything.

Grammatically, „læra“ takes a direct object in the accusative case, and „allt“ is neuter singular accusative, which fits this role.

If it were modifying a masculine plural noun like „hlutir“ (things), you’d see a different form:

alla hlutina (all the things) – masculine plural accusative
but here we just have allt = everything.

Why is it „á einum degi“ and not „í einum degi“? What does „á“ do with time expressions?

Both „á“ and „í“ can be used with time, but they have different typical uses.

In „á einum degi“, „á“ expresses roughly “within / in the space of” a length of time:

á einum degi – in one day / within one day
á einni viku – in one week

The idea is the entire time span as a limit or container for the action. That fits with “You can’t learn everything in one day.”

„í“ is more like “in / during” a period, often focusing on when something happens, or that it continues throughout that period:

Ég vann í allan dag. – I worked all day (during the whole day).

In this particular sentence, „á einum degi“ is the idiomatic way to say “in one day / within a single day” as a time limit.

Why are the forms „einum“ and „degi“ used? What cases are they?

Both „einum“ and „degi“ are in the dative singular:

einn (one) – masculine
- nominative: einn dagur
- accusative: einn dag
- dative: einum degi
- genitive: eins dags
dagur (day) – masculine noun
- nominative: dagur
- accusative: dag
- dative: degi
- genitive: dags

The preposition „á“ in this time-expression meaning (“in / within a period”) governs the dative case, so both the numeral and the noun must appear in the dative:

á einum degi – in one day
á tveimur dögum – in two days

So the form is determined by the preposition „á“ + its case requirements + singular masculine noun dagur.

Could I say this in another way, like using „geta“ instead of „hægt“?

Yes. A very natural alternative would be:

Maður getur ekki lært allt á einum degi.

Literally: One cannot learn everything in one day.

Notes:

„maður“ here means “one / people in general / you”, not specifically a male person.
„getur“ is the 3rd person singular of „geta“ (can, be able to).
The meaning is very close:
- Það er ekki hægt að læra allt á einum degi.
- Maður getur ekki lært allt á einum degi.

Both mean that it’s not possible to learn everything in a single day, just with slightly different structures: one with impersonal „það er hægt“, the other with „maður getur“ (“one can”).

Is „ekki hægt að…“ always negative, or can I use „hægt að…“ positively too?

You can absolutely use „hægt að…“ without „ekki“ for a positive meaning:

Það er hægt að læra íslensku.
It is possible to learn Icelandic.
Það er hægt að gera þetta á einum degi.
It is possible to do this in one day.

The basic pattern is:

Það er hægt að… – It is possible to…
Það er ekki hægt að… – It is not possible to…

Only the presence or absence of „ekki“ changes the polarity (positive vs negative); the rest of the structure is the same.

How would I pronounce the main tricky parts: „það“, „að“, and „degi“?

Very roughly (not strict IPA, just guidance):

„það“
- þ is like th in “thin”.
- ð (at the end) is often quite soft or almost dropped in casual speech.
- Many learners approximate it as something like “tha(th)” with a very light final sound.
„að“
- The vowel is like a in “father”.
- The final ð is usually very soft; it can sound almost like a slight friction or even disappear, especially in fast speech.
- You might hear something close to “a(th)” with the th very weak.
„degi“
- d as in English “day”.
- e is like e in “get” but often a bit tenser/longer.
- gi here is pronounced with a soft g + y, roughly like “dyi” or “gey-i”; you can think of it as “day-yi”.

Sentence rhythm: Icelandic normally puts the main stress on the first syllable of full words:

ÞAÐ er EKKi HÆGT að LÆra ALLT á EINum DEgi.