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HISTORICAL. VIEW OF THE
subject to perpetual change. By this effort of mentalabstraction, man produces, as it were, within himself anew intellectual creation; and this work, great and ab-struse as it may perhaps appear, is yet actually moreor less involved in the commonest comparison of things,and in the use of the very terms of which civilised lan-guage is formed. There are departments of enquiry ofa perfectly abstract and intellectual origin ; such as puremathematics; others, which essentially require only someone or two simple principles or data derived from ourexperience, on which, without extraneous aid, it is theirprofessed design to construct a system ; such as logicaland ethical science : in these the process of classificationbegins from the first principles adopted, and descends toindividual cases and particular facts. In other branches,on the contrary, which originate in observation and col-lection of facts, the classification begins from the com-parison of facts, and must he guided wholly by thenature of their different varieties of which it takes cog-nisance : from these it ascends to the more general factsand comprehensive laws.
The leading principle of the Aristotelian philosophywas precisely that of the former of these two classes.Hence, in its proper and legitimate province, it attained,in the hands of its great founder, to the highest perfec-tion : and the systematic forms which it gave to dialec-tical logic, or the theory of oonelusiveness ; to ethics, orthe theory of morals as deduced from some high firstprinciples of the nature of moral good; and to othersubjects admitting of the same mode of investigation,have to the present day commanded the admiration ofall capable of appreciating them; and have retainedtheir pre-eminence amid all the boasted improvementsof subsequent ages.
The same principles, however, were wholly inap-plicable to physical enquiry; the very circumstancewhich gave them their peculiar value in moral scienceobviously rendered them so, and the main fault in theAristotelian physics was precisely not hearing in mind