It's the idea of Plato: our soul/mind (whatever we call it) can be viewed as two horses: one, very beautiful, the other not. And we are sitting on the carriage and have to manage the two horses in order to work together... This may be the reason why we can be happier than animals, but also the reason why we can be much more sad than them Also it is the reason why only we humans have religions.Ideas of Spock, Hirgoyen, Plato, Aristoteles, Heidegger, Miller, the Script, the Beatles... And a dedication to the actor Robin Williams who, after a life with periods of drugs abuse, finally decided to take his own life. To be or not to be.