Traditional logic was first developed by Aristotle and systematised (somewhat differently) by the mediaeval school persons. It was thought to be all there was to logic by most until the end of the nineteenth century (until G. Frege, for example, came out with a version of modern logi8c in his Concept-Writing (Begriffsschrift). The assumption of traditional logic was that all propositions (sentences) are of a subject - predicate form (strictly, SUBJECT TERM + COPULA + PREDICATE TERM: for example, fist + are + backboned mammals). This exclusive emphasis on the subject - predicate form is though misleading, and the underlying cause of mistaken metaphysics by many modern logicians (vice versa for some recent critics of modern logic). Traditional logic is concerned with immediate and mediate inferences between (subject - predicate) propositions. Immediate inference is from one (premise) to one (conclusion) with the two terms of the premise both appearing in the conclusion. Mediate inference involves more premises with the use of "mediating", or middle, terms that do not appear in the conclusion. The sylloquism, the primary study of traditional logic, is an argument in which the premises connect the subject and predicate of the conclusion by means of a middle term.