 The different operations of the intellect producing different linguistic units are studied in Aristotle’s different logical works: the simple significative expression (simplex sermo significativus or the dicibile sine complexione), significative of one of the ten genera of things, is the subject-matter of the Categories; the declarative sentence (or the dicibile ordinatum cum dicibili interpretatione enuntiativa) is dealt with in the Perihermeneias; and the syllogism (or the dicibile ordinatum cum dicibili in complexione duorum extremorum) in the Prior Analytics. The syllogistic form—which Aristotle presents in the Prior Analytics—can then be applied to any matter whatsoever, probable or necessary (DOS 502). The Posterior Analytics presents the demonstrative syllogism, made of necessary matter; the Topics the dialectical syllogism of probable matter; and the Sophistical Refutations deals with sophistical matter, i.e., fallacious reasoning (DOS 503).