The heart is often used as a symbolic representation of emotion, preferably love. After all, the heart is what keeps the human body alive by steadily pumping blood and distributing it all out through the body. And what is a man without love? Without a companion? What is a man meant to be when he is nothing except alone? But what use is a heart to an immortal god who knows nothing about love? The air he breathes in never escapes his hollow lungs, and the blood that's meant to spread throughout him stays still. He is a walking, heartless corpse. And it's hard to do anything without a heart.