Every language has some way of showing the function of nouns and pronouns within a given sentence. Some languages, such as modern English, rely heavily on word order and prepositions whereas other languages rely on declensions. Declensions are the changes that occur to the endings of articles, pronouns, possessives, adjectives, nouns etc. to show their function in a given sentence.  (Changes that occur to verbs are called conjugations).

Declensions in Modern English

Modern English has retained declensions mostly in pronouns only. Look what happens to the word “he” as it goes through its three manifestations for English as its function in the sentence changes from subject, to object to possessive.

1. He is a pilot.                     ‘He’ as subject-the person/thing doing the action

2. I see him.                          ‘Him’ as object-the person/thing receiving the action

3. His friend is here.          ‘His’ showing possession

Declensions in Modern German

German features one extra case to distinguish direct from indirect objects. Indirect objects receive an action indirectly; it shows to/for whom something is done. English relies on word order or prepositions to make this distinction.

Therefore, German has four cases in total each of which has been given a Latin name: subject = nominative case, direct object = accusative case, indirect object = dative case, possessive = genitive case.

1. Er ist Pilot.                        ‘Er’ as subject of the sentence.  = nominative

2. Ich sehe ihn.                    ‘Ihn’ as direct object                      = accusative

3. Ich gebe es ihm.             ‘Ihm’ as indirect object                = dative

4. Das Ei des Mannes.   ‘Des Mannes’ as the possessor   = genitive

The advantage of the case system found in German is more flexibility with word order:

Ich sehe ihn./Ihn sehe ich. = I see him.

Objects of Prepositions:

In German, nouns and pronouns can also become objects of specific prepositions forcing them into the accusative, dative or genitive case (the nominative does not have any prepositions) depending upon the preposition used. One must memorize with which case each of the prepositions is associated.

1. Ich lebe ohne einen Hund. = Accusative

2. Ich lebe mit einem Hund.   = Dative

List of Prepositions by Case:

Accusative

durch (through), entlang (along), ohne (without), um (around, at), gegen (against), für (for)

Dative

aus (from), ausser (except), bei (at, near), mit (with), nach (after), seit (since, for),  von (from, by), zu (to),  gegenüber (across from)

Two-Way 

These prepositions may be used with either the accusative or the dative case.  The accusative is used if there is motion from point A to B whereas the dative is used if there is no motion, or motion within a restricted area i.e. pacing back and forth.

in (into, in), über (over, above), an (to, onto, on), unter (under, below), auf (onto, on), vor (in front of), hinter (behind), zwischen (between), neben (next to)

Genitive 

trotz (despite), während (during), wegen (because of), (an)statt (instead of)