This form of a Dativ is called a "Pertinenz-Dativ". It is used if the objet of the sentence is belonging to someone or something. Generally there exists an (almost) equivelent Genitiv construction. "Pertinenz-Dativ" referring to the object being a body part of a person: Sie sieht ihm in die Augen. = Sie sieht in seine Augen. = She looks into his eyes. "Pertinenz-Dativ" referring to the subject being a body part of a person: Mir tut der Kopf weh. = Mein Kopf tut weh. = My head aches. "Pertinenz-Dativ" referring to the subject being a thing belonging to a person: Da geht euch der Hut hoch. (Song text using a fixed expression, no equivalent Genitiv construction.) = That will turn you on. "Pertinenz-Dativ" referring to a thing belonging to a thing: Er zersticht den Autos die Reifen. = Er zersticht die Reifen der Autos. = He destroys the tires of the cars.

There is no "his" in this sentence. I found a "him". Because of that it is dative case. "Ich sah ihm in die Augen." - "WEM sah ich in die Augen?" = Dativ sah (sehen) = looked /saw (to look /to see) There would be a "his" (sein/seine) if the sentence was "Ich sah ihm träumerisch in seine (/in die) Augen." "I dreamfully looked into his (/the) eyes."

Hello Yujin, all four cases in German depend on simply three things: - Subject (always nominative) - verbs: - nominative (example "sein", "werden"; Er ist der neue Direktor.) - accusative (example "haben"; Er hat einen neuen Hut.) - dative (example "gehören"; Das Buch gehört dem Nachbarn.) - genitive (example "bedürfen" = brauchen; benötigen; Das bedarf deiner Hilfe.) - prepositions - accusative (example "für"; Das Buch ist für dich.) - dative (example "zu"; Er geht zu der Bank.) - genitive (example "trotz"; Wir gehen trotz des schlechten Wetters spazieren.) There is also one group of prepositions which is either a. or d., depending on the question is something being put somewhere or stationary in a place. Furthermore, in spoken German some prepositions tend to be used with dative instead of "rule-book-rules" genitive. Lastly, there are many verbs used in conjunction with a preposition. They have to be learned seperately.

You can use Dativ when it is possible to ask "Wem?" (whom)

"Sehen" (past tense: "Sie sah") is usually with accusative. "Sie sah ihn." (She saw him - meaning: her eyes perceived him). "Sehen" with dative has a different meaning. "Sie sah ihm in die Augen" (She looked in his eyes - meaning: her look went from her eyes to his eyes) This is somewhat similar to: "Sie warf ihm Sand in die Augen" (She threw sand in his eyes)