Se kestää vain hetken.

the moment

Breakdown of Se kestää vain hetken.

• se: it
• vain: only
• kestää: to take (time)

Questions & Answers about Se kestää vain hetken.

Why is it "hetken" and not "hetki"?

Because Finnish uses the genitive singular to express a bounded duration with verbs like kestää (to last/take). Think of it as “for X time”:

• Se kestää tunnin. (It lasts an hour.)
• Se kestää viikon. (It lasts a week.) So hetki (moment) becomes hetken (“for a moment”). The nominative hetki is not used for this duration meaning.

Which case is "hetken" exactly—genitive or accusative?

Morphologically it’s the genitive singular of hetki. In this time-measure use, grammars often call it an “adverbial genitive.” You may also see it analyzed as the -n “accusative,” but for learners it’s best to remember: genitive form for a specific, bounded duration.

Could I say "Se kestää vain hetkeä" or "Se kestää vain hetki"?

• Se kestää vain hetki is ungrammatical; nominative doesn’t work for duration.
• Se kestää vain hetkeä (partitive) isn’t idiomatic here. Partitive suits unbounded amounts, e.g. Se kestää tunteja (“It lasts for hours”). For “a (single) moment,” use hetken.

What does each word correspond to?