56 ARISTOTLE. 



which is itself derived from the theory respecting 

 the origin of general ideas. He always observes facts 

 with attention^ compares them with great precision^ 

 and endeavours to discover the circumstances in 

 which they agree. His style^ moreover^ is suited to 

 his method : simple, precise, unstudied, and calm, it 

 seems in every respect the reverse of Plato's ; but it 

 has also the merit of being generally clear, except in 

 some places where his ideas themselves were not so.^' 

 In one of his treatises, Aristotle divides na- 

 tural bodies into those possessing life, and those 

 destitute of that principle, — into animate and in- 

 animate. He considers soul as the vital energy or 

 vivifying principle common to all organized bodies ; 

 but distinguishes in it three species. Thus, in plants 

 there is a vegetative, in animals a vegetative and 

 a sentient, in man a vegetative, a sentient, and a 

 rational soul. The functions of nutrition and ge- 

 neration in plants and animals he attributes to the 

 vegetative soul ; sense, voluntary motion, appetite, 

 and passion, to the sentient soul ; the exercise of 

 the intellectual faculties, to the rational soul. 



His ideas of anatomy and physiology were ex- 

 tremely imperfect. Thus, he supposed the brain to 

 be a cold spongy mass, adapted for collecting and 

 exhaling the superfluous moisture, and intended for 

 aiding the lungs and trachea in regulating the heat 

 of the body. The heart is the seat of the vital fire, 

 the fountain of tlie blood, the organ of motion, sen- 

 sation, and nutrition, as well as of the passions, and 

 the origin of the veins and nerves. The blood is 

 confined to the veins; while the arteries contain 



* Biographie Universelle. 



