32 INTRODUCTION. 



any definite form, or constituted a body of doctrine, 

 until the time of Alexander the Great. At this 

 epoch the illustrious Aristotle collected the obser- 

 vations of his predecessors ; added to them those, 

 more extensive and more important, which were 

 made by himself; and, although deeply engaged in 

 the study of other subjects, succeeded in collecting 

 a mass of facts, and in eliciting from them general 

 principles, the accuracy of many of which might 

 surprise us, did we not reflect that, in this depart- 

 ment at least, he followed the true method by which 

 the physical sciences have in our times received so 

 vast an augmentation. He, however, stands alone 

 among the writers of remote antiquity in this field ; 

 for, if others followed in his steps, their works have 

 been lost. 



Among the Romans, by whom the sciences were 

 carried from Greece to Western Europe, there must 

 have been many naturalists of considerable attain- 

 ments ; but the only writer of that nation whose de- 

 scriptions have come down to us is Pliny the Elder, 

 who flourished under Vespasian. His books on natu- 

 ral history are compiled from the writings of others, 

 and may be considered as a general collection of all 

 that was known in his time. Although he must 

 have possessed opportunities of observing the many 

 rare animals that were brought from all parts of the 

 world to Rome, it does not appear that, by original 

 observation, he added much to the mass of facts ; 

 still he may be viewed as marking the second epoch 

 in the history of zoology, more especially as his 

 works supplied the materials out of which natural- 

 ists in later ages have constructed their systems. As 

 to iElian, a Greek writer, whose treatise was also a 

 6 



