Learn Hardcore Esperanto: Kiam mi revenas el la urbo, mi eniras la hejmon kaj fermas la pordon malrapide, por ne veki la infanon. - When I return from the city, I enter the home and slowly close the door, so as not to wake the child.

Why is revenas in the present tense? In English I might say “when I come back” or “when I get back”, which can refer to the future. Shouldn’t it be revenos?

In Esperanto, Kiam mi revenas… with the present tense usually describes:

a habitual action:
Kiam mi revenas el la urbo, mi eniras la hejmon…
= Whenever / When(ever) I come back from town, I go into the house…
or a general situation that is true whenever that condition happens.

If you want to stress a single specific future time, you can use the future:

Kiam mi revenos el la urbo, mi eniros la hejmon.
= When I come back (that time in the future), I will go into the house.

So:

revenas → general / repeated / “whenever”
revenos → one particular future occasion

Why do we say el la urbo and not de la urbo after revenas?

Both el and de can be translated from, but they’re used differently:

el = out of, from the inside of something
- Mi revenas el la urbo. – I return from the city (from being in the city).
- Mi eliris el la domo. – I went out of the house.
de = from, in a more general sense: source, origin, person, direction
- Mi ricevis leteron de li. – I got a letter from him.
- Mi venas de Londono. – I come from London (as my origin).

Because you’re literally coming out of the city where you were, el la urbo is the natural choice here.

Why is there la before urbo, hejmo, pordo, and infano?

La is the definite article, like English the. Here, each noun refers to a specific, known thing:

la urbo – the city (the one we have in mind, not just “a random city”)
la hejmo – the home / house (my particular home)
la pordo – the door (the main door of my home, understood from context)
la infano – the child (some particular child everyone already knows about)

You would drop la if you were speaking more generally:

urbo – a/the city in general
hejmo estas grava – home is important (home in general)
infanoj dormas – children sleep (children in general)

Why mi eniras la hejmon and not something like mi iras hejmen? What’s the difference?

There are two different patterns here:

eniri (ion) – to enter (something)
- Mi eniras la hejmon. – I enter the home / I go into the house.
- eniri is transitive, and la hejmon is its direct object.
iri hejmen – to go home
- Mi iras hejmen. – I go home / I’m going home.
- hejmen is a direction (accusative of direction, without any preposition).

Nuance:

eniri la hejmon focuses on the moment of crossing the threshold, stepping into the home.
iri hejmen focuses on going towards home; it doesn’t necessarily emphasize the act of stepping inside.

In your sentence, the idea is that you enter the home at that moment, so mi eniras la hejmon fits well.

Why is it la hejmon and not just hejmon or hejme?

Different forms of hejmo express different ideas:

hejmo – home (as a noun: a home / the home)
hejme – at home
- Mi estas hejme. – I’m at home.
hejmen – (to) home (direction)
- Mi iras hejmen. – I’m going home.
la hejmo / la hejmon – the home (a specific one: my/our home, from context)

In mi eniras la hejmon:

eniri needs a direct object, the thing being entered.
la hejmon marks that object (accusative -n) and shows it’s a specific home (with la).

So:

Mi eniras la hejmon. – I enter the (my) home.
Mi iras hejmen. – I go home.
These are grammatically and slightly stylistically different.

Why eniras la hejmon instead of iras en la hejmo?

Both are possible, but not equivalent:

eniri la hejmon
- eniri = enter
- la hejmon = direct object
  → Shorter, more idiomatic when you mean “enter/go into (a place).”
iri en la hejmo
- iri = go
- en la hejmo = in the home (location you go into)
  → Understandable, but less compact; in normal style people usually say eniri la hejmon.

Esperanto tends to use verbs like eniri, eliri, transiri instead of iri en, iri el, etc., when there’s a natural compound verb available.

Why is it malrapide and not malrapida after fermas la pordon?

In Esperanto:

-a = adjective → describes nouns
- malrapida pordo – a slow door (nonsense here, except metaphorically)
-e = adverb → describes verbs, adjectives, or other adverbs
- fermi malrapide – to close slowly

Here we’re describing how the action is done:

fermas la pordon malrapide
= (I) close the door slowly

So the adverb form malrapide is required, not the adjective malrapida.

Could I put malrapide earlier, like mi malrapide fermas la pordon? Is that still correct?

Yes, that’s correct. Word order is fairly flexible in Esperanto.

All of these are grammatically fine:

Mi malrapide fermas la pordon.
Mi fermas la pordon malrapide.
Malrapide mi fermas la pordon.

Differences are mainly in rhythm and emphasis:

Putting malrapide right before fermas slightly emphasizes the manner of the action.
At the end (…pordon malrapide) it can sound more narrative, like you’re adding the detail afterward.
At the very beginning (Malrapide mi fermas…) it strongly emphasizes slowly.

Your original version is perfectly natural.

In por ne veki la infanon, why is veki in the infinitive instead of vekas or vekus?

Por + infinitive (a bare verb in -i) is the standard way to express purpose when the subject is the same in both parts:

Mi fermas la pordon malrapide, por ne veki la infanon.
= I close the door slowly in order not to wake the child.

Patterns:

por fari / por veki / por dormi – in order to do / to wake / to sleep (purpose)
vekas / vekis / vekos / vekus – finite forms (I wake / I woke / I will wake / I would wake), not used directly after por in this kind of construction.

So veki is the correct form after por to show the goal or purpose of the main action.

Why isn’t there an -n on veki? In veki la infanon, only infanon has -n.

The -n (accusative ending) is used on nouns and pronouns, not on verbs.

veki – verb, infinitive form = to wake
la infano → la infanon – noun in direct-object role

In por ne veki la infanon:

veki is the verb, so no -n.
la infano is what gets woken; it’s the direct object of veki, so it takes -n → la infanon.

You never add -n to a verb form in Esperanto.

What’s the difference between por ne veki la infanon and por ke mi ne veku la infanon? Are both correct?

Both are grammatically correct, but they’re used differently:

por ne veki la infanon
- Same subject as the main clause.
- Literally: in order not to wake the child.
- Concise and very common.
por ke mi ne veku la infanon
- Uses por ke
  - subjunctive (here: veku).
- Common when the subject in the purpose clause is different from the main subject:
  - Mi parolas mallaŭte, por ke li ne vekiĝu.
    – I speak quietly so that he won’t wake up.
- With the same subject, por ke mi ne veku la infanon is grammatically fine but sounds heavier / more formal and is usually unnecessary.

So in your sentence, por ne veki la infanon is the natural, preferred form.

Is the ne in por ne veki la infanon in the right place? Could it be por veki ne la infanon?

The normal placement is exactly as in the sentence:

por ne veki la infanon – in order not to wake the child.

If you say:

por veki ne la infanon – in order to wake not the child,

then you’re negating la infanon specifically, as if you mean “to wake someone, but not the child.” That’s a different meaning.

So:

To negate the verb / whole action, put ne before the verb: ne veki.
Your original word order is correct and idiomatic.

Why is mi not repeated before fermas? In English we can omit it only in very informal writing, but here it seems required by grammar.

In Esperanto, you don’t need to repeat the subject if it stays the same; it’s very normal to omit it:

Mi eniras la hejmon kaj fermas la pordon.
Li sidas sur la seĝo kaj legas.

You would repeat it only for clarity or emphasis:

Mi eniras la hejmon, kaj mi fermas la pordon. (more emphasis on “I” doing both)

So the omission of mi before fermas is not informal or sloppy; it’s standard Esperanto style.