have you ever tuned a guitar? you tune the strings to the ones next to them by holding off the according fret and pitching until the two neighboring strings have the same sound. if your pitch is perfect, playing one string will make the other one vibrate. i like to think that when you listen to certain songs, and it's almost like you can *feel* the music inside your body, it's because the song has literally 'struck a chord' inside of you. that you have that exact same pitch and feeling somewhere deep inside, and that's why you can feel it. certain songs just resonate with me that way...
bizarre, eh?