"To lose a brother is to lose someone with whom you can share..." — Yann Martel quote meaning

To lose a brother is to lose someone with whom you can share the experience of growing old, who is supposed to bring you a sister-in-law and nieces and nephews, creatures who people the tree of your life and give it new branches. To lose your father is to lose the one whose guidance and help you seek, who supports you like a tree trunk supports its branches. To lose your mother, well, that is like losing the sun above you. It is like losing--I'm sorry, I would rather not go on.