 For a medieval master like Brito, the science of logic is first and foremost contained in Aristotle’s organon (see entry on  Aristotle's logic). Hence, Brito’s account of logic as a science must explain the division of the organon into six treatises as a reflection of a division of the syllogism into its different kinds (the demonstrative syllogism, the dialectical syllogism, etc.) and its constituent parts (simple words, assertions, etc.). Accordingly, Brito’s first division of logic proceeds as follows: the syllogism considered only with regard to its moods and figures is the subject matter of the Prior Analytics. The syllogism considered according to the alethic modality of its premises is the subject matter of the Topics and of the Posterior Analytics, the former dealing with the syllogism from probable premises and the latter with the syllogism from necessary premises. The syllogism from apparently probable premises is, in turn, the subject matter of the Sophistical Refutations. Now, since the syllogism can also be analyzed with respect to its constituent parts, the Categories deals with its simple parts—simple words—insofar as they can be sorted into different kinds (substance, quality, quantity, etc.). Finally, the De interpretatione deals with the complex parts of the syllogism—assertions that become its premises and conclusion—as well as with the simple parts of the assertion, i.e., the subject and predicate terms (QsP; see Ebbesen &amp; Pinborg 1981–1982: 301 and 303).