“Logic is named from the Greek word _logos_, which has a twofold interpretation. For _logos_ means either _sermo_ or _ratio_; and therefore logic may be termed either a _scientia sermotionalis_ or a _scientia rationalis_. _Logica rationalis_ embraces dialectic and rhetoric, and is called _discretiva_ (argumentative and exercising judgment); _logica sermotionalis_ is the genus which includes grammar, dialectic and rhetoric, to wit, discursive science (_disertiva_).”[455] The close connection between grammar and logic is evident. Logic treats of language used in rational expression, as well as of the reasoning processes carried on in language. Its elementary chapters teach a rational use of language, whereby men may reach a more deeply consistent expression of their thoughts than is gained from grammar. Yet grammar also is logic, and based on logical principles. All this is exemplified in the logical treatises composing the Aristotelian _Organon_, which the Middle Ages used. First comes Porphyry’s _Isagoge_, which clearly is bound up in language. Likewise Aristotle’s _Categories_ treat of the rational and consistent use of language, or of what may be stated in language. Next it is obvious that the _De interpretatione_ treats of language used to express thought, its generic function. The more advanced treatises of the _Organon_, the _Prior_ and _Posterior Analytics_, the _Topics_, and _Sophistical Elenchi_, treat directly and elaborately of the reasoning processes themselves. So one perceives the grammatical affinities of the simpler treatises in the _Organon_. The more advanced ones seem to stand to them as oratorical rhetoric stands to elementary grammar. For the _Analytics_, _Topics_, and _Sophistical Elenchi_ are a kind of _eristic_, training the student to use the processes of thought and their expression in order to attain an end, commonly argumentative. The prior treatises have taught the elements, as it were the orthography and etymology of the rational expression of thought in language; the latter (even as syntax and rhetoric), train the student in the use of these elements. And one observes a nice historical fitness in the fact that only the simpler treatises of the _Organon_ were in common use in the early Middle Ages, since they alone were necessary to the first stage in the appropriation of the substance of patristic and antique thought. The full _Organon_ was rediscovered, and retaken into use in the middle or latter part of the twelfth century, when men had progressed to a more organic appropriation of the patristic material and what they knew of the antique philosophy.