Rees maintains that six numbers in particular govern our universe, and that if any of these values were changed even very slightly things could not be as they are. For example, for the universe to exist as it does requires that hydrogen be converted to helium in a precise but comparatively stately manner--specifically, in a way that converts seven one-thousandths of its mass to energy. Lower that value very slightly--from 0.007 percent to 0.006 percent, say--and no transformation could take place: the universe would consist of hydrogen and nothing else. Raise the value very slightly--to 0.008 percent--and bonding would be so wildly prolific that the hydrogen would long since have been exhausted. In either case, with the slightest tweaking of the numbers the universe as we know and need it would not be here. I