So far as we know, Aristotle had no one name for all these investigations. "Analytics" is only applied to the _Prior_ and _Posterior Analytics_, and "logical," which he opposed to "analytical," only suits the _Topics_ and at most the _Sophistical Elenchi_; secondly, while he analyzed syllogism into premises, major and minor, and premises into terms, subject and predicate, he attempted no division of the whole science; thirdly, he attempted no order and arrangement of the treatises into a system of logic, but only of the _Analytics_, _Topics_ and _Sophistical Elenchi_ into a system of syllogisms. Nevertheless, when his followers had arranged the treatises into the _Organon_, as they called it to express that it is an instrument of science, then there gradually emerged a system of syllogistic logic, arranged in the triple division--terms, propositions and syllogisms--which has survived to this day as technical logic, and has been the foundation of all other logics, even of those which aim at its destruction. The main problem which Aristotle set before him was the analysis of syllogism, which he defined as "reasoning in which certain things having been posited something different from them of necessity follows by their being those things" (_Prior Analytics_, i. 1). What then did he mean by reasoning, or rather by the Greek word [Greek: logos] of which "reasoning" is an approximate rendering? It was meant (cf. _Post. An._ i. 10) to be both internal, in the soul ([Greek: ho esô logos, en tê psychê]), and external, in language ([Greek: ho exo logos]): hence after Aristotle the Stoics distinguished [Greek: logos endiathetos] and [Greek: prophorikos]. It meant, then, both reason and discourse of reason (cf. Shakespeare, _Hamlet_, i. 2). On its mental side, as reason it meant combination of thoughts. On its linguistic side, as discourse it was used for any combination of names to form a phrase, such as the definition "rational animal," or a book, such as the _Iliad_. It had also the mathematical meaning of _ratio_; and in its use for definition it is sometimes transferred to essence as the object of definition, and has a mixed meaning, which may be expressed by "account." In all its uses, however, the common meaning is combination. When Aristotle called syllogism [Greek: logos], he meant that it is a combination of premises involving a conclusion of necessity. Moreover, he tended to confine the term [Greek: logos] to syllogistic inference. Not that he omitted other inferences ([Greek: pisteis]). On the contrary, to him (cf. _Prior Analytics_, ii. 24) we owe the triple distinction into inference from particular to particular ([Greek: paradeigma], example, or what we call "analogy"), inference from particular to universal ([Greek: epagôgê], induction), and inference from universal to particular ([Greek: syllogismos], syllogism, or deduction). But he thought that inferences