What they discover is that there is no separation between self, environment and others. Life depends on having a heart, lungs, mind and other people. They are all part of self. Life also calls for environmental parts such as food, air, water and warmth. They are as important to self as the physical parts such as mind and heart.
Life depends on others.
Other People provide all kinds of life sustaining assistance. They defend us, love us and feed us when we are not able to do these thing for ourselves. So basically our environment and interdependence on others are all part of our whole self. If we neglect others care, we neglect self. When others get sick, self gets weaker.