Symbolism, Imagery, Allegory
Help, I'm Alive… My Heart Keeps Beating like a Hammer
Tris thinks about heartbeats a lot. She thinks of heartbeats when someone else is about to die: "I am thinking of the heart. Not of my heart anymore, but of Eric's, and how empty his chest will sound when his heart is no longer beating" (16.6). She also thinks of heartbeats when she thinks she is about to die: "I hear my heartbeat, fast and strong. Soon, where that steady rhythm was, there will be nothing" (35.25). She talks about heartbeats so much, it starts to seem like an obsession.
Describing her telltale heart is the closest Tris comes to talking about her emotions sometimes. As someone who grew up in a divided world, she has separated her biological functions from her emotional ones, so it's not surprising that she talks about love, fear, feelings, and death in strictly biological terms.
She's just as divided as her world is, and she doesn't really understand the connection between emotions and physical reality. Your heart might beat faster when you're scared or when you're in love, and that's a good example of a physical reaction that is emotionally motivated. Tris doesn't get the connection.