sentences: if something does not contain something else, then that something else cannot be lost in that something
docs: another_way_to_say_separates_things is divides_objects. abandoned_thing is tangible_thing. space is nothing_for_everything. thing is substance. separated_thing is divided_thing. else is river. no_thing is nothing_yet_no_one_knows. things is often_not. nothing_here is like. lost_river is tangible_thing.