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his notion of the effects of the relative lightness
In the soul itself are included the nutritive faculty, which is the property of vegetables; the sensitive, generally of animals; the locomotive, enjoyed by the more perfect creatures; and the rational, which characterizes man. Here, it is evident that he intends, by the term soul,” the source equally of life as of intellect, and, throughout his deductions, the tendency to reduce all impulses to the laws of matter, is perceptible, since only material similes are
employed. The soul, he considers, the result of the perfect action of the functions and organs of the body, but still the essential cause of the latter ; it is defined to be “neither body nor extended magnitude, but something of body and in magnitude,” the centre of all the perceptions which the corporeal frame brings into it. But the body derives its own sensations through the flesh, and this last acts as a medium, also, to convey impressions to the soul, the vital heat of the body originating in etherwhich he considered as a fifth element, “neither heavy nor light, but of which the heaven and the stars are composed, and which, like them, is eternal”—while the organ which this vital heat first affected, and whence sensation proceeded, was not the brain, but the heart. It is clear, from the division of the intellect already noticed, how far he acknowledged the immortality of the soul ; for, if pure or active intelligence might exist separate from matter, yet the mind, so far as it consisted of affections, he deemed to be perishable as matter; and even the immortality which he admits, is represented in terms so obscure, that his views on this subject are far less clear than Plato's, and will not bear comparison with those of Socrates.
Aristotle's mathematical works consisted only of two small treatises, upon “ Indivisible Lines," and “Mechanical Questions ;' nevertheless the science so completely entered into his method, that we often find, in his other works, mathematical demonstration employed.
Logic, as enunciated by this master, in the "Art of Reasoning," rested upon the fundamental assumption that truth and falsehood do not depend upon things, but upon words, especially when the latter are combined into propositions, and, therefore, he regulated inquiry by first establishing fixed rules of accurate definition. To effect this, he reduced all classes, under which everything might be brought, to the ten Categories or Predicaments of Quantity, Quality, Relation, Action, Passion, Where, When, Position, Possession, Substance; and even if this attempt at classification be imperfect, yet it shows the earliest system of examination into the forms, as well as the objects, of thought. Besides these, however, he adopted five Predicables, or different kinds of one class—the Genus, Species, Difference, Property, and Accident; thus, man” is a species of the genus "animal;" his being rational is a "property," as it is inseparable ; his colour, white, is a
"difference," as it is separable from his nature;
John," is an accident." Upon these investigations into the nature of proportions, Aristotle founded the syllogism, or theory of reasoning, which he defined to be ciation in which, from certain admitted propositions, a necessary conclusion is drawn distinct from them, and yet employing the same idea,” thus:
“ Sin leads to misery,
Sabbath-breaking is sin, Therefore, Sabbath-breaking leads to misery.” In this manner, demonstration was developed by a rule, which, taking certain axioms or admitted facts, drew from them an undeniable inference; the proper subject of such demonstration being those universal attributes of particular things, which make them what they are. Logic also entered closely into his physical speculation as to the method which he took to distinguish between the general laws of nature and their exceptions, and he regarded it as the more perfect science, on account of its freedom from those variations to which the other was subject. It enters equally into his ethical treatise, and into his masterly discussion of the passions in his Rhetoric, which last science, in fact, had never been reduced, until
the time of Aristotle, into its essential subject, the composition of argument itself. Having established syllogism as a method of demonstrating fact, he treats rhetoric as the science of persuasion ; and hence discusses under this head the nature of persuasives generally.
Collecting herein the several arguments most commonly effectual to influence the mind, he is necessarily obliged to examine also, in this extraordinary work, the variety of disposition at different periods of human life, in order to adapt a proper kind of argument to each
i so that really the whole resolves itself into an inquiry concerning every kind of influence by which the mind of man is swayed. He divides the subject into the deliberative, suited to political debates, the judicial, and the demonstrative; the last including the topics by which the orator gratifies his hearers ; but the extent of matter in the Rhetoric is so vast, that it has been justly styled a magazine of intellectual riches : “The recesses and windings of the hidden region of the human heart are explored; its caprices and affections—whatever tends to excite, to suffer, to amuse, to gratify, or to offend it-have been carefully examined. The whole is a text-book of human feeling, a