Simple method of including a file that bypasses macro expansion

Hi,
 
I am relatively new to m4, but can't seem to find an equivalent to include that
bypasses macro expansion.
 
Suppose file 'a' contains
  hello world
and file 'b' contains
  goodbye world
and in my m4 I have defined
  define(world,and).
I a macro which I will call 'oinclude' such that
  include(a) oinclude(b)
expands to
  hello and goodbye world.

Is there a simple method?
 
Thanks,
 
John