From 1647 onwards, in several of his writings, Boxhorn elaborated the idea that Scythian was the original mother language of Persian, Greek, Latin, the Germanic languages, Turkish, Welsh, Lithuanian, Russian and Latvian (cf. Boxhorn 1647).
2011, Gerda Haßler, Gesina Volkmann, History of Linguistics 2008: Selected Papers from the Eleventh International Conference on the History of the Language Sciences (ICHoLS XI), 28 August -2 September 2008, Potsdam, John Benjamins Publishing Company, page 159