Learn Hardcore Finnish: Kirjailijan tarina oli tärkein syy, miksi valitsin tämän kirjan. - The author's story was the main reason why I chose this book.

It shows possession: kirjailijan tarina literally means “the author’s story.” In Finnish you add -n (genitive ending) to kirjailija to indicate “of the author.”

Why is tärkein used instead of tärkeämpi?

tärkein is the superlative form of tärkeä (“important”), meaning “most important.” tärkeämpi is the comparative (“more important”) and would compare two things, not express “the most.”

Why is there a comma before miksi?

The comma separates the main clause from the subordinate (relative) clause introduced by miksi. It marks “why I chose this book” as additional information about the syy.

Why do we use miksi instead of koska or siksi että?

After syy (“reason”) Finnish uses relative question words like miksi (“why”) or expressions like jonka takia (“for which reason”). koska and siksi että both mean “because” but introduce causal clauses, not relative clauses.

Why is tämän kirjan in the accusative case (which looks like genitive) rather than nominative or partitive?

valitsin (“I chose”) is a telic verb indicating a completed action, so its direct object takes the accusative. In Finnish the accusative singular of a noun appears identical to the genitive (kirjan). You wouldn’t use the partitive because you’re referring to the book as a whole.

Could we replace miksi with jonka takia or josta?

Yes. You could say Kirjailijan tarina oli tärkein syy, jonka takia valitsin tämän kirjan or …syy, josta valitsin tämän kirjan. jonka takia is particularly common for “the reason why.”

Why does tärkein syy match in form?

Adjectives in Finnish agree with the noun in case and number. Here syy is nominative singular, so the superlative adjective takes the nominative singular form tärkein.

Why is valitsin in the past tense?

Because the speaker chose the book in the past. valita is “to choose,” and valitsin is its first‐person singular past (preterite) form: “I chose.”