Everyone knows that Germanic languages are related. It is not so well known however how the relation shows. Speyer asks how the Germanic languages came into being, for the relations between them and what unites and what distinguishes them. The author establishes the facts from the earliest known stages of Germanic languages: Gothic, Old Icelandic, Old English and Old High German. Speyer depicts the languages by phenomena. He does not deal with each language separately but with aspects that appear in a few languages or are characteristic for one language. The phenomena are distinguished into three fields: phonology, morphology and syntax.