Hermann Osthoff (1847–1909) and Karl Brugmann (1849–1919) were central figures in the circle of German scholars who rejected a doctrinal approach to the study of linguistics. They came to be known as the Neogrammarian school. At the core of their work was the theory that European languages, together with a subset of languages found in central and southern Asia, have a common origin in a single prehistoric language. They called this ancestor Indo-Germanic (known today as Indo-European) and claimed that its descendants are all related to one another by varying degrees of closeness. This six-volume elaboration of this thesis was published between 1878 and 1910. The preface to Volume 1 (1878) contains the 'Neogrammarian Manifesto' which states categorically that there are no exceptions in the laws of sound change, while new languages are formed only in relation to already existing languages.
Vorwort; 1. Das verbale Suffix 'a' im Indogermanischen; 2. Formassociation bei Zahlwörtern; 3. Zur Geschichte der Personalendungen; 4. Die arische Passivbildung; 5. Kleine Beiträge zur Declinationslehre.