 Hendrik Louwerisz.Spieghel, an influential 16th-century grammarian, tried to reform and standardize the Dutch case system in his book on grammar, "Twe-spraack van de Nederduitsche Letterkunst" ["Dialogue on the Low German art of letters"] (1584).In particular, Spieghel wanted to create a distinction in grammatical function between two existing forms of the definite article, "de" and "den", having "de" pertain to subjects and "den" to objects.