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For instance , Thales suggested in the 7th century BCE that water was the ultimate underlying substance from which everything is derived ; Anaximenes subsequently made a similar claim about air .
 Thales, Anaximenes
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: location, person, organization 
Text: {0} 
Answer:
 Thales, Anaximenes