Learn Hardcore Polish: Kiedy w domu jest ciemność, latarka leży zawsze na tym samym stole. - When there is darkness at home, the flashlight always lies on the same table.

Kiedy w domu jest ciemno
= “When it is dark in the house.”
This is the most natural, everyday way to say it. Ciemno works like a predicative adverb (“it’s dark”).
Kiedy w domu jest ciemność
= literally “When there is darkness in the house.”
This sounds more formal, literary, or dramatic, because ciemność is a noun (“darkness”).

In normal spoken Polish, a native speaker would almost always say: > Kiedy w domu jest ciemno, latarka zawsze leży na tym samym stole.

In English we say “When it is dark in the house”. Why doesn’t Polish use an “it” here?

Polish usually does not need a dummy subject like English it:

English: It is dark.
Polish: Jest ciemno. (literally “Is dark.”)

Polish allows the verb to appear without an explicit subject in such impersonal expressions describing weather, light, temperature, etc.:

Jest zimno. – It’s cold.
Było jasno. – It was bright.
W domu jest ciemno. – It is dark in the house.

So no word for “it” is needed; the structure itself tells you it’s an impersonal “it”-situation.

Does „kiedy” here mean “when” or “whenever”? How does Polish show that this is a repeated, habitual situation?

In this sentence kiedy can be understood as “when(ever)”:

Kiedy w domu jest ciemność…
“When(ever) there is darkness in the house…”

Polish usually uses present tense together with kiedy (or gdy) to express a general, habitual relationship:

Kiedy jestem głodny, jem. – When(ever) I’m hungry, I eat.
Kiedy mam czas, czytam. – When(ever) I have time, I read.

So even though the verb is in the present tense, context + kiedy gives it a habitual meaning, similar to English “whenever”.

Why is there a comma after „ciemność”: „Kiedy w domu jest ciemność, latarka leży…”?

Because the sentence consists of two clauses:

Kiedy w domu jest ciemność – subordinate clause (time condition)
latarka leży zawsze na tym samym stole – main clause

In Polish, a subordinate clause introduced by kiedy, gdy, ponieważ, że, etc. is separated by a comma from the main clause.

Word order can change, but the comma stays:

Kiedy w domu jest ciemno, latarka zawsze leży na tym samym stole.
Latarka zawsze leży na tym samym stole, kiedy w domu jest ciemno.

Both need the comma.

Why is it „w domu” and not something like „w dom” or „w domem”? Which case is this?

W domu uses the locative case (locative singular of dom = domu).

The preposition w (“in”) can take:

Locative – for location (where?)
- w domu – in the house
- w szkole – at school
- w szafie – in the wardrobe
Accusative – for movement into (where to?), but only in some specific expressions (like w las “into the forest”, more poetic/archaic). With dom, motion is usually expressed with do domu (“to the house”).

Here we are talking about a location, not movement, so we use w + locative:
> w domu – in the house.

Why is it „na tym samym stole” and not „na ten sam stół”? What case is being used after „na” here?

The preposition na can take accusative or locative, depending on the meaning:

Accusative – with movement onto something (where to?):
- Położyłem latarkę na ten sam stół. – I put the flashlight onto the same table.
Locative – with location on something (where?):
- Latarka leży na tym samym stole. – The flashlight is lying on the same table.

In your sentence, the flashlight is not moving; it’s just lying there. So na + locative is used:

stół (nominative) → stole (locative)
with modifiers: na tym samym stole – on the same table.

How does „tym samym” work grammatically in „na tym samym stole”? What is „samym”?

Tym samym is a combination of:

tym – a form of the demonstrative pronoun ten (“this/that”),
samym – a form of sam meaning “same”.

Both must agree in case, gender, and number with the noun stół:

stół – masculine singular
na (location) → locative case → stole
so we need masculine singular locative forms:
- ten → tym
- sam → samym

Hence:
> na tym samym stole – on the same table.

Why is the word order „latarka leży zawsze” and not „latarka zawsze leży” or „zawsze latarka leży”? Which is most natural?

Polish word order is fairly flexible, but there are neutral preferences.

For adverbs of frequency like zawsze (“always”), the most typical neutral orders are:

Latarka zawsze leży na tym samym stole.
Zawsze latarka leży na tym samym stole. (more emphasis on always)

Latarka leży zawsze na tym samym stole is still correct, but it can sound slightly less neutral, with a bit of emphasis on leży (the fact that it lies / is located there).

So if you want the most everyday, neutral version, use:

Kiedy w domu jest ciemno, latarka zawsze leży na tym samym stole.

Could I say „latarka jest zawsze na tym samym stole” instead of „latarka leży zawsze na tym samym stole”? What’s the difference between „leżeć” and „być” here?

Yes, you can say:

Latarka jest zawsze na tym samym stole.

It is correct and natural. The difference is slight:

leżeć – “to lie” (be in a lying position)
It adds a bit of physical detail: the flashlight is lying on the table, as an object.
być – “to be”
More neutral: the flashlight is on that table; no mention of position.

In practice:

Latarka leży na stole. – The flashlight is lying on the table.
Latarka jest na stole. – The flashlight is on the table.

Both are fine; leżeć is just a bit more descriptive.

How can I tell that „latarka” is feminine? Are there any rules for this kind of noun?

Latarka is feminine. A common rule of thumb:

Nouns ending in -a are usually feminine, especially if they refer to inanimate things:
- książka (book) – fem.
- szklanka (glass) – fem.
- latarka (flashlight) – fem.

There are some masculine nouns ending in -a (e.g. mężczyzna, “man”), but they are fewer and often refer to male persons.

Knowing that latarka is feminine helps with agreement:

ta latarka – this flashlight (feminine form ta, not ten)
mała latarka – small flashlight (feminine mała, not mały).

In English we say “the flashlight” or “a flashlight”, but Polish just says „latarka”. How do you know if it’s “the” or “a”?

Polish has no articles (a/an/the), so latarka by itself could mean:

a flashlight, or
the flashlight, depending on context.

Context tells you whether the object is:

newly introduced (more like “a flashlight”)
already known / specific (more like “the flashlight”)

If you really want to make it clearly specific, you can use a demonstrative:

ta latarka – this (particular) flashlight
ta sama latarka – the same flashlight

In your sentence, because it talks about a known, regularly used flashlight, the best English translation is “the flashlight”, even though Polish just says latarka.

Why is „ciemność” in the nominative case after „jest”? Could it be another case?

After the verb być (“to be”) in sentences like “X is Y”, both X and Y are in the nominative:

To jest dom. – This is a house.
To jest latarka. – This is a flashlight.
W domu jest ciemność. – In the house (there) is darkness.

So ciemność is nominative singular. You would not change it to another case after jest in this type of sentence.

Could I also say „Kiedy w domu jest ciemno…” or „Gdy w domu jest ciemno…” instead of „Kiedy w domu jest ciemność…”? Is „gdy” different from „kiedy”?

Yes, and these alternatives are actually more natural:

Kiedy w domu jest ciemno, latarka zawsze leży na tym samym stole.
Gdy w domu jest ciemno, latarka zawsze leży na tym samym stole.

Kiedy and gdy often mean almost the same (“when/whenever”). Differences:

kiedy – the most common, neutral in speech and writing.
gdy – slightly more formal or literary in many contexts, but still very common.

In most everyday sentences, you can freely replace kiedy with gdy without changing the meaning.

Why is there no pronoun like „ona” (she/it) before „leży”? Could I say „Ona leży zawsze na tym samym stole”?

Polish normally drops subject pronouns when the subject is clear from context:

Latarka leży na stole. – The flashlight lies on the table.
(no pronoun needed)

You could say:

Ona zawsze leży na tym samym stole.

but this usually happens when:

you’re contrasting ona (she/it) with something else, or
latarka was already mentioned and you now replace it with a pronoun for stylistic reasons.

In your sentence, adding ona would sound a bit unnecessary or emphatic. The most natural form is simply:

Latarka zawsze leży na tym samym stole.