In contrast to the fairly fully developed theories of phonological and morphological description achieved by classical antiquity, no general theory of syntax (sentence structure) was presented in the works of the classical grammarians such as Apollonius Dyscolus and Priscian, but rather a voluminous and detailed discussion of individual constructions in which words of different classes were involved. The creation and exposition of a general theory of sentence structure was a central part of the work of the late mediaeval speculative grammarians, and their identification of supposition (grammatical subject) and opposition (grammatical predicate) and the relation of compositio between them, together with other syntactic relations and the general relation of dependentia, provided a framework for the syntactic analysis of all the basic sentence patterns of Latin (and, by implication, of other languages). Though their system of syntactic analysis was not maintained by their successors, several key terms and concepts in syntax today are direct inheritances from mediaeval speculative grammar.