Questions & Answers about Kirjoitan päiväkirjaa käsin.
The base (dictionary) form is päiväkirja (diary).
In Kirjoitan päiväkirjaa käsin, päiväkirjaa is in the partitive singular.
Finnish often uses the partitive case for the object of a verb when:
- the action is ongoing, incomplete, or unbounded, or
- you are talking about some amount of something, not a clearly finished whole.
Here, kirjoitan päiväkirjaa is understood as:
- I am (in general / right now) engaged in the activity of writing my diary,
not I wrote the entire diary (from beginning to end).
So päiväkirjaa (partitive) fits this ongoing / habitual action better than the “whole completed object” form.
Kirjoitan päiväkirjan käsin uses päiväkirjan (genitive/accusative singular), which presents the diary as a whole, completed object.
Kirjoitan päiväkirjaa käsin
= I (am) write(ing) my diary by hand.
(Focus on the activity, not on finishing the whole diary.)Kirjoitan päiväkirjan käsin
= I will write the diary (the whole thing) by hand.
(Implies a completed result, like a project: I’ll produce a diary, and it will be handwritten.)
The second sentence sounds more like you are planning to produce a full diary as a finished product, which is a bit unusual in everyday speech. The first one is the normal way to say that you keep / write in your diary by hand.