(foreach x ( (things heat thermodynamics)
                (chemicals atoms chemistry) 
                (objects mass physics)
                (words letters printing) )
      (substitute
         "If you don't know what $(first x) have $(second x) and what
         $(first x) don't (or if you think that all $(first x) have
         $(second x)), then you're going to be stuck as far as starting 
         a science of $(third x)."  ) )