It means that even if we are too old to care for ourselves anymore and we have to depend on strangers to bathe us, clean us up when we are no longer in control of bodily functions, it totally strips us of our "dignity", self-respect, independence and it depresses the hell out of an old person to be treated as a child, just because we are physically unable to care for ourselves does not mean we lost lost all our mental faculties and to be treated with less than "dignity" is about the worst feeling an old person can have. God Bless "old people", without them we wouldn't be here.
