For centuries, poets and philosophers have sensed that the heart is at the center of our lives. Saint-Exup?ry wrote, "And now here is my secret, a very simple secret: it is only with the heart that one can see rightly; what is essential is invisible to the eye." Even when we?re not consciously communicating with others, our physiological systems interact in subtle and surprising ways. Did you know that the electromagnetic signal produced by your heart is registered in the brain waves of people around you?