My first actual encounter with ghosts was while I was in France, staying in an old convent in Cahors.  It was lunchtime and I was heading across the vestibule from the dining area into the laundry, when I stopped dead in my tracks at the sight of 5 monks, similarly dressed in brown cowled robes, heads down, faces hidden, sweeping the floor in unison.  I have absolutely no doubt that they were there - I was not afraid - and during my stay there over the next two weeks, I had other visitations from an old woman, who I later learned had died there.  She simply terrified me.  
                 Heavy sleep often brings me these surreal encounters, fading in and out of clarity - a 'mirage' of sorts.  So real are these visions that I can mistake their questionable authenticity for that of certainty.  My mind allows me to see the possibilities and partake in the moment.  I recall fragments of my dreams here, fleeting moments that have stayed with me.