János Sajnovics and Sámuel Gyarmathi are usually appreciated as the first scholars to have proven the relatedness of the Finno-Ugric languages. This paper argues that the significance of
Demonstratio
and
Affinitas
lies not so much in their contribution to the idea of relatedness (since that had been in the air before them) as in the synthesis they give. Sajnovics and Gyarmathi arranged previously known but unsystematic information and arguments into a clear and coherent structure. They applied the principles of linguistic comparison very consciously and pointed out the importance of the evidence of grammar. The most important aspect of their work is the way it anticipated the methods of modern linguistics: deduction, logical inference, philological methods with Sajnovics, and reconstruction and the assumption of hypothetical transitional forms with Gyarmathi. In its purpose, Sajnovics’s book is closer to genealogical comparison, Gyarmathi’s to typological comparison
