| If he can witness the effect it has, he's not "believing" anything, he's observing and drawing conclusions based on those observations.  Nor would I even say one can't "touch" the wind.  I touch it all the time, I can feel it quite readily.  It's not just an observable phenomenon, it's an easily observable phenomenon. 
				__________________'He who receives an idea from me, receives instruction himself without lessening mine; as he who lights his taper at mine, receives light without darkening me.' 
-TJ
   |