Why is it, when we're experiencing a certain emotion, we tend to gravitate toward music that has a similar

Many people are afraid of what they don't know. They reject it or make umptions about it. In a similar way, people like to be able to relate to things--a similarity makes this a familiar feeling, so music that relates to the emotional state they're in is comforting. If they're sad, it helps to cheer them up. If they're happy, it ups their mood even more. If they're angry, it cools them down. The upbeat, happy music tends to go with happier lyrics; slow music, sadder lyrics; hard, fast music, angrier lyrics--it's just a mold today's music tends to fit into. Whatever the situation, people like to relate, and music can do just that.