ARISTOTLE. 57 



an aerial spirit ; and by nerves he means tendons, 

 nerves,, and arteries, — in short, strings of all kinds, 

 as the name implies. The heart has three cavities ; 

 in the larger animals it communicates with the 

 windpipe, or the ramifications of the pulmonary- 

 artery receive the breath in the lungs and carry it 

 to the heart. Respiration is performed by the ex- 

 pansion of the air in the lungs, by means of the in- 

 ternal fire, and the subsequent irruption of the ex- 

 ternal air to prevent a vacuum. Digestion is a kind 

 of concoction or boiling, performed in the stomach, 

 assisted by the heat of the neighbouring viscera. 



It is perhaps impossible at the present day, when 

 the investigation of nature is so much facilitated by 

 the accumulated knowledge of ages in every depart- 

 ment of physical science, by the commercial rela- 

 tions existing between countries in all parts of the 

 globe, by a tried method of observation, experiment, 

 and induction, and finally, by the possession of the 

 most ingenious instruments, to form any adequate 

 idea of the numerous difficulties under which the 

 ancient naturalist laboured. On the other hand, 

 he had this great advantage, that almost every 

 thing was new ; that the most simple observation 

 correctly recorded, the most trivial phenomenon 

 truly interpreted, became as it were his inalienable 

 property, and was handed down to succeeding ages 

 as a proof of his talents, — a circumstance which must 

 have supplied a great motive to exertion. 



The History of Animals is undoubtedly one of 

 the most remarkable performances of which phy- 

 sical science can boast. It must not, however, be 

 imagined that it is a work which, replete with truth 

 and exhibiting the well-arranged results of accurate 



