if something requires something else then that something requires a source of that something else
fault is tangible_thing. environment is tangible_thing. else is river. source_materials is source. goods is tangible_thing. change is when_one_thing_becomes_another_thing. space is what_between_else. naturally_occurring_tangible_substance is tangible_thing. matter is tangible_thing. electrical_conductor is tangible_thing.