The German linguist and mythologist Heymann Steinthal (1823-99) taught at the University of Berlin (today Humboldt-University Berlin) and was especially engaged with Wilhelm von Humboldt and his linguistic works. He was a co-founder of the Berliner Gesellschaft für Anthropologie, Ethnologie und Urgeschichte (Berlin Society for Anthropology, Ethnology and Prehistory). This innovatory volume, published in 1855, draws a connection between the disciplines of linguistics and psychology, and further relates them to the issue of logic. The three parts of the book deal with the nature of grammar, its relation to logic and the connection of grammar and linguistics to cognitive behaviour. Finally Steinthal discusses the idea of linguistics as ethnopsychology. Pursuing this concept, he, with his brother-in-law Moritz Lazarus, co-founded the journal Zeitschrift für Völkerpsychologie und Sprachwissenschaft (Journal for Ethnopsychology and Linguistics) in 1860, thus laying the foundations for a promising new area of research.