13948
From the time of Herodotus a minority of geographers have rejected the three-continent system ( Europe , Africa , Asia ) on the grounds that there is no substantial physical separation between them .
 Herodotus, Europe, Africa, Asia
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: location, person, organization 
Text: {0} 
Answer:
 Herodotus, Europe, Africa, Asia