Jacob Grimm

Jacob Grimm was a German philologist who, working alongside his brother Wilhelm, established the comparative method as a rigorous tool for reconstructing the history of the Germanic languages. His Deutsche Grammatik set out what became known as Grimm's Law, a systematic set of consonant shifts distinguishing the Germanic branch of Indo-European from its sister branches, giving the comparative method one of its first and most famous demonstrations that sound change is regular rather than arbitrary. He and Wilhelm are also widely known outside linguistics as collectors of the fairy tales that bear their name, work that grew from the same philological interest in the German language's oldest recoverable forms.