Locke, into two classes, sensible and rational; intending by the first, those which are derived immediately from sensation, and by the second, those obtained by reflection, or the action of the mind in itself. These are subdivided into probable and improbable, doubtful and false. The phantasies, or images of external objects, are either immediate, as when we look on the individual himself; or consequential, as when the view of a portrait calls up the image of the person it represents; or compounded, as in the case of a landscape; augmented or diminished, as when we look at a giant or dwarf.

135. Having laid the foundation of his logical system, in these and many similar metaphysical distinctions and speculations, Zeno proceeded to the more definite object of the science, and inquired into the origin of language-the varieties of vocal sounds-words, as arbitrary signs of ideas, the elementary parts of speech, the relations, affinities, powers, and modifications of terms, when variously arranged in sentences-and the properties of style. According to this philosopher, the chief excellencies of style are, perspicuity, propriety, brevity or compression, decorum and elegance: its principal faults— barbarisms, solecisms, and anomalies. From words separately considered, or as grouped together in sentences, he advanced to definitions, their various kinds and essential qualities; in which he seems to have closely followed the track marked out by Aristotle, in his books of " Interpretation" and "First Analytics." The distinctions and rules suggested on this subject, will be found in almost

every treatise on logic, which has been since published.

136. The next step in the logical system of the Stoics, was the classification of the objects of human knowledge into genera and species; terms which were then employed in nearly the same sense as that attached to them by modern logicians. The principal divisions of genera are, real and imaginary existences; and these are again classified by terms which nearly correspond with the words substances or subjects, qualities or adjuncts, modes, and relations. Then passing once more from thoughts to words, all objects of thought that can be expressed are termed dicibles; which admit of innumerable modifications, such as interrogative, imperative, hypothetical, &c. Advancing to propositions, the nature and properties of predicates (technically termed categorems) are minutely described, and their varieties distinguished. Of these, the most important are axioms, which are either simple or compound, possible, probable, necessary, connective, disjunctive, with a thousand other equally trifling distinctions.

137. Reasons, or arguments, occupy nearly the same place in the logic of the Stoics, as syllogisms in that of Aristotle. They are divided into conclusive and inconclusive, the former of which (as the terms import) denote those arguments which are legitimately conducted and lead to the discovery of truth; and the latter, those which are imperfect or sophistical. Great attention was paid by the Stoics, as well as all other classes of ancient dialecticians,

to the various kinds of Sophisms, the detection and refutation of which are of so great importance in debates. These were divided into the quiescent, the false, the occult, the inexplicable, the reciprocal, the defective, with many others.

Finally, Method, or the general mode of conducting arguments, occupied an important place in the dialectics of Zeno. The chief distinctions made on this subject were, the philosophical and the vulgar. The philosophical method consisted in the scientific employment of all the didactic rules previously suggested, relative to definition, division, and syllogistical reasoning: the vulgar, or popular method, might be pursued either by continuous oration or colloquial discussion. The former method is recommended as best fitted to the exposition of the arts and sciences, and the latter as most useful in disputation and controversy.

138. The sketch of the logical systems of the Academic, Peripatetic, and Stoic sects, which has been attempted, may perhaps suffice for the review of this department of ancient science. It would have been easy to extend it, by alluding to the dialectics of other sects, or by presenting the juvenile reader with analyses of other logical works; but it is conceived that this would be neither desirable nor advantageous in so elementary a work as the present. The only additional work on the subject which claims a distinct notice, is, the "Canonica" of Epicurus, which is partly metaphysical and partly dialectic. Having premised that "Truth is of two kinds, that which respects real existences, and that

which consists in a perfect agreement between our mental conceptions and the nature of things," he proceeds to enumerate and classify the criteria by which truth may be discerned. These are the three following, which are the great instruments employed by the human mind in forming its judgments, viz. sensation, preconception or anticipation, and passion or affection. On each of these, several general principles, termed by Epicurus canons, are laid down as rules to assist the understanding in its search after physical or moral truth. These canons, though highly curious, and in some degree useful, it would be tedious to enumerate.*

SECTION V.

GENERAL REMARKS ON THE DIALECTICS OF THE
ANCIENTS.

139. THE preceding review of the dialectics of Plato, Aristotle, Epicurus, and Zeno, may, it is feared, seem dry and uninteresting to such juvenile readers as have not paid any attention to logic. For their sakes, therefore, we shall step aside for a moment from the direct object of these pages, which is, the recital of historic facts connected with the

A summary of the principal contents of the Canonica of Epicurus, will be found either in the ancient biographical history of Diogenes Laertius, in the philosophical writings of Sextus Empiricus, or in Stanley's Lives of the Philosophers, p. 851-856.

progress of general knowledge, in order to shew that this science, (forbidding as it may appear, and formidable as was the array of technical terms, with which it was formerly encumbered), is of great utility and importance. That a contrary opinion should be entertained by many, can excite no surprise, when it is considered that, in succeeding ages, this art was solely applied to the most frivolous and useless logomachies; that the study of logic superseded, at one time, every other exercise of the human mind, and even usurped the place of the Sacred Volume itself; and that, in modern times, names of considerable authority can be cited, by whom the dialectic art has been held in sovereign contempt. To remove such prejudices, it is only necessary to turn from the contemplation of the abuses and perversion of this art, which were the combined result of ignorance and folly, to the objects which it proposes to attain, and for the attainment of which, under the guidance of sound judgment, it is well adapted. It may be proper, too, to distinguish not only between the interminable disputations of the Sophists, but also the scholastic refinements and subtilties of the Peripatetic philosophers, and the true science of logic.

140. The objects of logic, as stated by the ancients themselves, are, the exercise and improvement of the rational faculties, the exposure of error, and the discovery of truth; and who will say that these are objects of subordinate importance? With respect to the former of these, it is admitted that the mathematical sciences tend more directly and