Helmut Humbach
born in 1921, emeritus professor of Comparative (Indoeuropean) Linguistics at Johannes Gutenberg University Mainz (Germany), studied Indoeuropean and Classical Philology in Munich. In 1956 he was appointed to a chair at the University of the Saarland, in 1961 he accepted the chair at Mainz University. To the current formalism of linguistic prehistory, he preferred the philological and historical approach to texts of the past, which he consistently carried out in teaching and research. His expertise has been requested and welcome all over the world. The cooperation with his colleague Klaus Faiss enabled him to complete his life-long work on Zarathushtra but also that on Herodotus and Ptolemy.

Klaus Faiss
born in 1940, emeritus professor of English Philology at Johannes Gutenberg University Mainz (Germany), studied English and Romance Philology. After a three-year professorship at the Ruhr University Bochum, he accepted a chair at Mainz University in 1976 teaching English linguistics, both modern and historical, till 2006. His main fields of research are the history of the English language, especially morphology, word formation, and syntax as well as their interrelations. Owing to the collaboration with his highly estimated colleague Prof. Humbach, Klaus Faiss has developed a keen interest in Herodotus, Ptolemy, and Zarathushtra studies.