304 History of Philo sophy. 



Aristotle in many points differs from and combats the opinions of 

 Plato, and in no case more pointedly than in the refutation of his 

 doctrines of innate ideas. These, he says, cannot exist, but that the 

 operations of the mind inferred in Plato's philosophy by that deno- 

 mination are merely purer abstractions of Plato's second faculty, the 

 understanding, and are produced by a continuation of the same pro- 

 cess of induction that furnished us with the subordinate causes of 

 mental or physical phenomena. We derive all knowledge from in- 

 duction or demonstration. Demonstration is founded on general, 

 induction on particular notions. Of these the former are necessarily 

 a consequence of the latter. We obtain general principles by the 

 comparison and examination of particular cases, and build the reason- 

 ing of our demonstration on the axioms thus obtained. This doctrine, 

 though divested of the poetry of Plato's subtle and mystical IDEAS, 

 is consonant to the strictest logic and intelligible to plain sense, and 

 is therefore more fit to be cultivated than the romantic flights into 

 the regions of [the sublime which have rendered it doubtful whether 

 the disciple of Socrates understood himself. Aristotle may be con- 

 sidered the head of the empirical school, Plato the " chief of the 

 speculative school of philosophers. 



The regions of science had been gradually increasing in extent 

 and richness for some time previous to the appearance of Aristotle, 

 but it was reserved for him to make greater additions to each indi- 

 vidual department than were to be found in the accumulated know- 

 ledge of his predecessors in each. We possess only a part of his 

 labours, and these furnish materials for a cyclopasdia. Natural his- 

 tory, the useful and liberal arts, speculative science, moral philosophy, 

 are all particularly treated, and though there is no work actually on 

 mathematics, he constantly employs the reasoning of this department 

 of science. We shall best exhibit the services he has done to man- 

 kind by cursorily enumerating the subjects of some of his principal 

 treatises. His " History of Animals" consists of a vast collection of 

 interesting facts and examples in natural history, which still supplies 

 much useful information to the student, notwithstanding the aids that 

 have since been invented for the rendering observations more exact, 

 and which the ancients did not enjoy. The unassisted faculties were 

 the only instruments they were endowed with, and under such un- 

 favourable circumstances Aristotle classified and systematized a 

 world of facts which has provided future writers on the same subject 

 with an inexhaustible fund, whence to derive examples and confir- 

 mations of their theories. 



His books on " the Soul," " the Memory," " the Senses," " Sound," 

 " Colour/' " Dreams,'' &c., are equally valuable, but we must hurry 

 forward in our brief analysis. 



Under the term " Metaphysics," the stagyrite includes " the know- 

 ledge of first principles and final causes, in which consists wisdom. 

 Among the principles he lays down and supports by long arguments 

 may be stated the following : " No thing can be and not be at the 

 same time." " A thing must be or not be." " Causes of causes can- 

 not be assigned to infinity." From these principles he proceeds to 

 demonstrate the existence of a divine power, and opposing Plato in 



