I have been seeing the world through my two eyes. This condition is both unique but also common to all people. People wonder: How is the coincidence possible that among the billions of people I – especially and only I- can see the world as a set of opposite confronting things through my own two eyes, see my face only on a mirror, while everybody else seem simply to be external objects for my optical sense but also for my other senses! So, the subject is the thing that perceives with all available senses the surrounding objects and it can be either me or somebody else.