In Paris, Wilhelm von Humboldt encounters the Basque language, initially only in books, which differs fundamentally from the other European languages, and he investigates the effects that this deep a linguistic difference could have on man as a thinker. (…) The Basque language is the reason for him to take two research trips to the Basque region and the subject of his first linguistic analyses. The different “views of the world” (Weltansichten) or the “diversity of the structure of human language” are topics that Humboldt would continue to investigate for the rest of his life. While pursuing his Basque studies, he planned to write a description of the Greek language, but gave that project up to dedicate himself to American languages. His brother Alexander had brought home grammars and dictionaries from America, about which Wilhelm was supposed to write a treatise for Alexander’s comprehensive travelogue.
With a detour via the Chinese language, Egyptian hieroglyphs, and Sanskrit, Humboldt then came to study the Austronesian languages, the “languages of the South Seas” that his unfinished magnum opus “Über die Kawi-Sprache auf der Insel Java” (On the Kawi Language on the Island of Java) investigates. The introduction, published posthumously in 1836 under the title “Über die Verschiedenheit des menschlichen Sprachbaues und ihren Einfluss auf die geistige Entwickelung des Menschengeschlechts“ (On the diversity of human language construction and its influence on the mental development of the human species) sets out his legacy in terms of his insights into linguistics and the philosophy of language.