You would know what truly matters to a person based on what gives him or her joy. Succcess will give a lot of people joy. Accomplishments also. Money for sure. Popularity, maybe. For some it's finding love. Or maybe having your own children. Life has a lot to offer us and experiencing all of its blessings can give us great joy. Who wouldn't want that? But what if someone or something threatens all of that? Then we would know what truly matters.