People feel empty when their desires are not given. The heart of a man is like a vacant vessel and is to be filled with anything. Most of people try to fill their hearts with worldly things including pleasures, knowledge, money and honor. But they cannot be satisfied with those worldly things but desire some more. Only when you fill your heart with the truth, goodness, and love through listening to the word of God and practicing it, will emptiness leave you and true joy and peace come upon you.