THE LOGIC OF CLASSIFICATION. 241 Isidorus, Alcuin, John Scotus Erigena, Petrus Hispanus, &c. ; Hegel and certain moderns what do we find ? We find Aristotle assimilating himself to Socrates, and Hegel to Plato, and the Latins reproducing Aristotle or else running several significations alongside each other. We are, there- fore, thrown upon the logical arrangement. This would probably gather up the meanings into three groups as fol- lows : (1) Those that express a mode or method of attain- ing truth, together with a mental discipline ; (2) those that set forth the nature, the movement or the progress of truth itself ; (3) those that designate a branch of science. Under the first head would come (a) Socrates's cross-examination, or the clearing of people's notions by putting them through a series of interrogations, which, by first opening their eyes to their own ignorance, prepared the way for the discovery and reception of the truth (really, therefore, a species of Inductive Defining) ; (&) Aristotle's " dialectic," as de- scribed in the Topica, confined to the sphere of Opinion or the probable, in contradistinction to Demonstration ; (c) the " disputation " of the Schoolmen, by means of question and reply, interrogation and response, examination of proof and counter-proof. To the second head would be assigned (a) Plato's theory of Ideas, and (6) Hegel's movement of the Idea in the course of its expansion and development, in the threefold form of " affirmation, negation and the union of the two," " thesis, antithesis and synthesis," " identity, difference and combination ". Under the third head would be placed (a) the early Latin and Scholastic conception of Dia- lectic, which identified it with what we should now-a-days call Logic (although that term was formerly applied to Rhetoric as well, and was sometimes extended also to Grammar), and (5) that other Scholastic usage, which made Dialectic synonymous with "the pursuit of all the liberal arts". Turn, next, to the Classification of the Sciences. If we go back to early times, we find the division current into Theo- retical and Practical. This classification had certain obvious uses, and the convenience of it is attested by the fact that it is still in force, for general purposes, at the present day. But, obviously, it cannot plead the merit of being a strictly logical division ; for many sciences are both theoretical and practical, and it would be equally legitimate to place them in the one division as in the other. Faulty, however, though it be in this respect, it is perfection itself as compared with the next great historical classification that of the Stoics. The Stoics were above all things moralists, and everything they viewed from the ethical standpoint. They grouped the 16
