In the first part of the work, Mertian (1766–1843) studies the relationship between language and the way the mind operates. Whereas he is bound to Condillac and Liebniz in this part, the second part contains his real accomplishment: the attempt to find an appropriate definition of the »first principles» (grammatical categories), which is based on the nature of language itself. These efforts towards a universal grammer and its concise metalinguistic designation ensure this work a place in the present discussion on linguistic theory as well.