Once you play the blues, you'll understand what it feels like to have your soul speak through your instrument.  Blues music is highly emotional, raw, and captivating.  While the blues is known for expressing sadness or heartache, it can also be very alleviating for the soul.  This genre of music is simple in chord progressions yet heavy in improvisation within a specific musical key.  I highly recommend every musician to try the blues out at some point.