I have a problem understanding this German sentence:

Du musst an deine Mutter schreiben.

You must write to your mother.

It means you must write something (for example a letter) to your mother.

That something is the direct object (accusative case) and the person to whom the letter is written is the indirect object (dative case) here.

So, Mutter is dative case and dein should be deiner but it is deine, why? I don't understand it. I didn't find the preposition an in the list of accusative prepositions either.

  • 6
    If you didn't find the preposition AN in the list of accusative prepositions, you should probably consult another dictionary.
    – tofro
    Jun 7, 2023 at 13:26
  • 8
    The concept of direct and indirect objects doesn't exist in German.
    – user6495
    Jun 7, 2023 at 13:48
  • 2
    You may find "an" in the list of "two-way prepositions", that is, prepositions that can be used with accusatve or dative (and whose meaning changes depending on whether it's accusative or dative).
    – Uwe
    Jun 7, 2023 at 14:59

2 Answers 2


I'm thinking the reason you didn't see 'an' as an accusative preposition is because it's a Wechselpräposition aka variable preposition. That means it can take either the accusative or dative depending on context and meaning. In this case, 'deine Mutter' is the target or direction of the verb ('schreiben') and this implies that the noun takes the accusative case. As mentioned above, it's best not to think of direct or indirect objects in German grammar since those concepts cause more confusion than understanding. If you must describe an object then identify it by case, so 'accusative object' or 'dative object'. In this case the noun is part of a prepositional phrase so 'prepositional object' is apt. The case of a prepositional object is nearly always either accusative or dative, but genitive does appear sometimes. Which case to use depends on the preposition, and, when Wechselpräpositionen are involved, also on the situation. I'd advise looking up Wechselpräposition for more on which case to use with them. There is a so-called 'movement rule', but depending on how it's stated it can also cause more confusion than understanding. In this case there is no 'movement' but the noun is accusative, despite what some versions of the movement rule might say.

  • 2
    The movement rule causes confusion because it's wrong. There can be a lot of movement at the train station. It's about direction, not movement.
    – Olafant
    Jun 9, 2023 at 11:14
  • @Olafant - Could you please explain a little about the direction rule? Unfortunately, all textbooks refer to movement rules. Any article or link for me to read? Jun 12, 2023 at 21:08
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    @Nariman Asgharian - I checked my three favorite grammar sites on this and all three got it wrong, or not actually wrong but oversimplified and incorrect for this example. The problem with textbooks is that it's easy to write a rule that works most of the time and give examples of it working correctly, but more difficult to write a rule that covers everything you may encounter "in the wild". It seems like related issues have be covered here quite a few times, but I couldn't find a single answer that covers everything; perhaps a new question is in order.
    – RDBury
    Jun 13, 2023 at 2:17
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    PS. Herr Antrim pokes fun at how the "movement rule" is commonly taught in this YouTube video. Unfortunately I don't think his version is completely correct either, just less wrong than average.
    – RDBury
    Jun 13, 2023 at 2:24
  • @RDBury - Thanks for your explanations dear RDBury. I totally agree with what you said about the problem with textbooks. I haven't yet found any practical solution or rule for the so-called two-way prepositions. Currently, there is nothing better than memorizing some phrasal verbs which take accusative and dative cases. I think even the German natives can't recommend a 100% working solution and they just know the cases by heart. Herr Antrim has some amazing videos and I have watched some of them. I'm looking forward to hearing something new about the direction rule! Jun 13, 2023 at 16:08

It's not an object but a directional adverbial. You can tell that from the leading preposition an. This preposition requires accusative if a direction is meant and dative if a location or culprit is meant.

For a dative object, you had to leave out that an.

  • Du musst deiner Mutter schreiben.

That means your mom is who benefits from the letter. As that's what the dative object indicates: who benefits from the action.

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