 His 400-page dictionary of Egyptian-Semitic-Indo-European roots appeared in 1886.His essay "On the antithetical meanings of primal words" ("Ueber den Gegensinn der Urworte") was discussed by Sigmund Freud in an identically titled piece, which, in turn, was discussed by Jacques Derrida as a precursor to deconstruction's semantic insights.He also translated some of Shakespeare's works into German.