  For many medieval Aristotelians, the isomorphism between language, thought, and reality does not apply only to the derivation of the ten categories. A group of thirteenth-century thinkers commonly referred to as the modistae go well beyond Aquinas in this respect. Although there is little consensus on exactly who these thinkers are, most accounts include Martin of Dacia (d. 1304), John of Dacia (d. ca. 1280), Petrus Croccus (d. 1304), Michael of Marbais (fl. ca. 1300), Radulphus Brito (ca. 1270–1320), and Thomas of Erfurt (fl. ca. 1300). They are important in particular because of their views concerning the strong isomorphism between language and reality. For many of them this isomorphism is so profound that the boundaries between grammar, logic, and metaphysics are either non-existent or fuzzy. Thus, conclusions about the nature of things (reality) can be derived from grammatical (language) or logical (thought) considerations, just as Aquinas derives the ten ultimate categories of reality from ten modes of predication. As Sten Ebbesen describes it: “The basic idea of modism is this: each constituent of reality (each res) has a number of ways or modes of being (modi essendi) which determine the number of ways in which it can be correctly conceptualized; the ways in which it can be conceptualized (modi intelligendi) in turn determine in which way it can be signified” (Ebbesen 1998, 274). Christian Kloesel adds that by “discovering the logical structure and the causes of language, a modista tried to explain the essential nature and purpose of human speech and the ways in which words have meaning. [For the modistae thought] that the structure of language mirrors the structure of reality and the operations of the human mind” (Kloesel 1981, 130).