Roy,  
     Well, you are correct that the use  
of axioms in 20th century math and physics  
involved matters far from obvious, but   
from a history of thought perspective the  
concept of an axiom does date back (at least?)  
to Euclid, for whom they were assumptions  
thought to be obvious from internal analysis,  
even if later his axioms (or at least some  
of them) came to be viewed as synthetic   
propositions capable of empirical testing.  
  
Barkley Rosser