34 SCIENCE OF THE GREEKS. FT. I. 



Pliny wrote much on Natural History, but he did not make 

 many original observations. 



Galen, 131. There is still one more great man of 

 science whom we must mention as having studied at the 

 Greek school at Alexandria. This was Galen, one of the 

 most celebrated physicians of antiquity. He was born A.D. 

 131, at Pergamos, in Asia Minor, where he received a 

 liberal education, comprising all the branches of science 

 known to the Greeks. He then turned his attention to 

 medicine, and travelled to Smyrna, Corinth, and Alexandria. 

 After practising for some time in his native country he went 

 to Rome, where he became very famous. During his life 

 he is said to have written more than 500 valuable essays 

 on medicine and the human body. You will remember 

 that Erasistratus and Herophilus dissected the human body ; 

 but in the time of Galen this seems to have been forbidden, 

 and he was obliged to work upon monkeys and other 

 animals. Even from these, however, he learnt some very, 

 important facts. For instance, he discovered the difference 

 between the two sets of nerves which we have in our body, 

 called the nerves of sensation and the nerves of motion. 



Our bodies are provided with two sets of fine cords or 

 threads called nerves ; one set running from different parts 

 of the body to the spine and the brain, and the other set 

 running back from the spine and brain to the body. If 

 you touch a hot iron with your finger, the nerves of sensa- 

 tion, that is, of feeling, carry the message to your brain 

 that the iron is hot, and then instantly the nerves of motion 

 carry the message back from your brain to your finger, and 

 you snatch it away. If the nerves between your finger and 

 your brain had been cut or injured you would not feel pain 

 when you touched the hot iron, nor draw your finger away. 

 You will remember that Erasistratus had an idea that it is 



