1. The aim of the History of Ideas It is possible that a word remain the same when the meaning is different. It is also possible that the meaning is the same wher the word is different. This point of view is explored by the history of ideas. And the history of ideas tries to understand the meaning-system behind texts. This study is not limited to the reading of the letter texts, but tries to understand the non-letter texts or the non-letter objects. 2. The variety of the Germanic identity The variety of the Germanic identity is clear when we observe closely the treatment of myths in Germany and Northern Europe. German idealism was eager to use the materials of the Edda myths. But it was a threat for Scan- dinavian people. It was a kind of battle among identities. 3. Grund and Eksistens in the history of ideas in Northern Europe We can see from the history of idea in Northern Europe that the concept of Grund comes from the earth mother religion written in Germania by Tacitus. And the concept of Eksistens by Kierkegaard should be originally the idea of outlaw written in Icelandic sagas. Eksistens points to social discrimination, also.